bflfl    SEA 


EXCHANGE 


Studies  in  Dyeing  and 
Cleaning 


A  THESIS 


PRESENTED  TO  THE  FACULTY  OF  THE  GRADUATE  SCHOOL 
OF  CORNELL  UNIVERSITY  FOR  THE  DEGREE  OF 
DOCTOR  OF  PHILOSOPHY 


By 
DYER  BARKER  LAKE 


(Reprinted  from  the  Journal  of  Physical  Chemistry,  20,  761  (1916).) 


July,  1916 


Studies  in  Dyeing  and 
Cleaning 


A  THESIS 


PRESENTED  TO  THE  FACULTY  OF  THE  GRADUATE  SCHOOL 
OF  CORNELL  UNIVERSITY  FOR  THE  DEGREE  OF 
DOCTOR  OF  PHILOSOPHY 


By 
DYER  BARKER  LAKE 


(Reprinted  from  the  Journal  of  Physical  Chemistry,  20,  761  (1916).) 


July,  1916 


STUDIES  IN  DYKING  AND  CLEANING 


BY   D.    B.    LAKE 

Studies  on  the  displacement  of  adsorbed  substances  have 
been  made  quite  recently  by  Freundlich,1  and  by  C.  G. 
Schmidt.2  Freundlich  studied  the  adsorption,  by  charcoal, 
from  a  solution  containing  two  dissolved  substances.  The 
solutions  studied  contained  the  following  pairs  of  acids: 
oxalic  acid  and  acetic  acid;  oxalic  acid  and  succinic  acid; 
and  oxalic  acid  and  benzoic  acid.  They  found  that  each 
acid  diminished  the  adsorption  of  the  other;  in  other  words 
that  a  given  amount  of  one  acid  in  the  presence  of  another 
acid  was  adsorbed  less  by  charcoal  than  it  was  from  its  own 
solution.  From  this  it  was  concluded  that  each  acid  of  the 
pairs  studied  displaced  the  other  from  the  charcoal.  By 
the  same  method,  Schmidt  studied  the  adsorption  by  char- 
coal of  iodine  and  acetic  acid  dissolved  in  chloroform  and 
obtained  results  similar  to  those  of  Freundlich.  He  states 
in  general  that  if  a  dissolved  substance,  A,  is  adsorbed  by 
charcoal,  the  addition  of  a  substance,  B,  soluble  in  the  solvent, 
will  bring  about  a  displacement  of  A;  and  vice  versa.  He 
found  that  the  amount  of  the  two  dissolved  substances  ad- 
sorbed was  less  than  the  sum  of  the  amounts  adsorbed  sep- 
arately. 

These  experiments  seem  strongly  to  confirm  the  idea 
of  the  displacement  of  one  adsorbed  substance  by  another. 
This  displacement,  it  is  evident,  is  by  no  means  confined 
to  the  above  examples.  Among  the  many  interesting  cases 
where  it  would  seem  to  apply  is  that  one  relating  to  the 
adsorption  of  two  dyes,  under  certain  conditions,  by  a  fiber 
as  wool.  Thus  if  a  dyed  fiber  such  as  wool  is  treated  with 
another  dye  of  the  same  class  under  the  same  conditions, 
the  second  dye  seems  partially  or  completely  to  displace  the 


1  Van  Bemmelen's  Gedenkboek,  88  (1910). 

2  Zeit.  phys.  Chem.,  74,  731  (1910). 


364635 


762  D.  B.  Lake 

first  dye  as  indicated  by  the  change  of  color  of  the  dyed  fiber, 
and  the  mixed  color  of  the  final  bath. 

Preliminary  experiments  to  verify  this  matter  were 
carried  out  in  the  spring  of  1915  by  Miss  R.  R.  Murray. 
Miss  Murray  used  a  silk-wool  flannel  cloth,  the  warp  of  which 
is  wool,  the  woof  silk.  Briefly,  the  method  of  procedure  was 
to  put  a  piece  of  cloth  into  a  cold,  dilute  solution  of  the  first 
dye,  bring  to  a  boil  and  keep  at  that  temperature  for  one-half 
hour;  remove;  wash;  set  aside  a  piece  for  comparison,  and 
place  the  remaining  piece  in  the  fresh  bath  of  the  second  dye, 
in  which  the  cloth  received  the  same  relative  treatment  as 
in  the  first  case.  The  reverse  treatment  was  also  carried 
on  at  the  same  time.  "Thus  a  succession  of  displacements 
of  dyes  by  each  other  under  similar  conditions  was  obtained." 
Acid  and  basic  dyes  were  used.  Among  the  acid  dyes  used 
were:  acid  green  BBN,  acid  violet  3R,  crocein  orange  R, 
alkali  blue,  lanafuchsine,  cyanole  green,  and  brilliant  scarlet; 
among  the  basic  dyes :  safranine,  thioflavine  T,  brilliant  green 
and  emerald-green. 

Concerning  the  displacement  of  one  color  by  another  on 
wool,  the  work  seemed  to  show  that  crocein  orange  could  be  dis- 
placed by  acid  green  and  acid  violet ;  acid  green  by  alkali  blue ; 
thioflavine  T  by  safranine  and  brilliant  green;  and  safranine 
by  brilliant  green  and  emerald-green.  On  silk,  also,  a  color 
displacement  was  shown.  On  it,  acid  green  and  crocein 
orange,  acid  violet  and  crocein  orange,  brilliant  scarlet  and 
cyanole  green  displaced  each  other  in  the  order  named,  and 
in  the  reverse  order.  In  one  direction  only,  thioflavine  T 
was  replaced  by  safranine;  and  brilliant  green  and  safranine 
by  emerald-green.  The  color  changes  indicated  above  were 
clear  and  sharp.  With  both  the  wool  and  the  silk  there  were, 
in  addition  to  the  above,  several  cases  of  a  partial  displace- 
ment of  one  color  by  another.  On  wool,  there  was  the  case 
of  the  partial  displacement  of  acid  violet  by  crocein  orange; 
on  silk  that  of  safranine  by  thioflavine  T. 

From  the  evidence  of  the  fiber,  it  is  seen  that  in  many 
ccises  we  have  complete  displacement  of  one  color  by  another. 


Studies  in  Dyeing  and  Cleaning  763 

From  the  point  of  view  of  the  final  bath  also  the  work  seemed 
to  show  that  there  was  a  more  or  less  complete  displacement  of 
one  dye  by  another.  Thus  in  the  final  bath  from  the  fiber 
dyed  either  in  crocein  orange  or  acid  violet,  and  then  followed 
by  acid  violet  or  crocein  orange,  both  dyes  were  present  as 
indicated  by  the  color  of  the  final  bath  which  was  a  wine-red. 
As  with  acid  violet  and  crocein  orange,  so  with  the  other  dyes 
studied,  the  final  baths  always  contained  some  unadsorbed 
dye  and  some  "apparently  displaced  dye." 

Thus  it  is  seen  that  Miss  Murray's  work  brought  out  the 
interesting  question:  Does  one  dye,  under  the  experimental 
conditions  described,  displace  another  as  indicated  (i)  by  the 
change  of  color  of  the  fiber,  (2)  by  the  presence  in  the  second 
final  bath  of  the  two  dyes? 

In  the  fall  of  1915  additional  experiments  were  carried 
out  along  the  lines  indicated  above.  The  fiber  chosen  was 
pure  hank  wool,  and  was  used  as  bought.  At  room  tempera- 
ture, one  gram  of  the  wool  was  placed  in  the  dye  bath  of 
definite  volume  (50  cc)  and  concentration,  brought  to  the 
temperature  of  a  boiling  water-bath,  and  kept  there  for  one- 
half  hour.  The  dyed  fiber  was  then  removed,  thoroughly 
washed  in  distilled  water,  and  placed  in  a  bath  (50  cc)  of  the 
second  dye  of  definite  concentration,  and  the  same  treatment 
repeated. 

First,  an  account  will  be  given  of  the  attempts  to  bring 
about  color  changes  on  the  wool  fiber,  and  then  an  account 
of  the  apparent  displacement  of  one  dye  by  another  dye.  The 
dyes  used  in  the  greater  part  of  the  experiments  here  recorded 
were  those  sent  to  the  Physical  Chemical  Department  through 
the  courtesy  of  the  Schoellkopf ,  Hartford  and  Hanna  Company 
of  Buffalo,  N.  Y. 

On  the  wool  in  the  silk-wool  flannel  acid  violet  was  not 
displaced  completely  by  crocein  orange,  the  color  obtained 
being  a  "mixed  brown;"  accordingly,  experiments  were  first 
carried  out  with  these  two  dyes.  It  was  thought  that  by 
dyeing  the  fiber  in  a  comparatively  small  amount  of  acid 
violet  and  then  treating  this  dyed  fiber  by  varying  amounts 


764  D.  B.  Lake 

of  crocein  orange,  viz.,  10,  20,  30,  40  and  50  mg,  respectively, 
a  concentration  of  crocein  orange,  within  reasonable  limits, 
could  be  found  that  would  completely  displace  the  color  of 
the  acid  violet.  Negative  results  were  obtained;  that  is, 
in  no  case  was  the  final  color  of  the  fiber  that  of  pure  crocein 
orange.  At  the  concentrations  of  40  mg  and  50  mg  of  crocein 
orange,  however,  its  color  tended  to  predominate,  that  is, 
the  color  of  the  acid  violet  was  more  or  less  completely  masked. 
The  final  color  of  the  fiber  at  these  higher  concentrations  of 
crocein  orange  was  on  the  whole  of  a  light  brick-red. 

A  few  experiments  were  made  to  ascertain  the  minimum 
amount  of  acid  violet  with  which  the  fiber  could  be  dyed  in 
order  that  the  color  imparted  to  the  fiber  would  just  influence 
the  succeeding  crocein-orange  color.  The  concentration  of 
acid  violet  varied  from  5  mg  to  0.2  mg  per  50  cc,  while  that 
of  the  crocein  orange  was  kept  at  25  mg  per  50  ec.  The 
minimum  concentration  of  acid  violet  was  found  to  be  0.25 
mg.  This  experiment  brings  out  strikingly  the  comparative  in- 
tensity of  the  color  of  the  two  dyes  when  adsorbed  by  the  wool. 

Results  for  the  wool  dyed  in  a  bath  of  crocein  orange 
followed  by  acid  violet  were  somewhat  different  than  for  the 
above  experiments.  In  these  cases,  the  crocein-orange  color 
was  practically  although  not  completely  displaced  by  acid 
violet.  The  concentration  of  both  dyes  in  50  cc  was  25  mg, 
respectively.  To  learn  whether  by  prolonged  treatment  of 
the  dyed  fiber  by  the  second  dye,  a  complete  displacement  of 
the  first  dye  could  be  brought  about,  the  dyed  fiber  from  the 
crocein  orange  was  left  in  the  acid  violet  bath  at  the  tempera- 
ture of  the  dyeing  for  four  hours.  Twenty-five  milligrams 
of  each  dye  per  50  cc  were  used.  On  the  whole  the  result  was 
negative;  that  is,  even  after  this  prolonged  treatment  of  the 
dyed  fiber  in  acid  violet,  the  acid  violet  did  not  entirely  mask 
the  color  of  the  crocein  orange.  However,  these  results  are 
in  harmony  with  those  of  the  preceding  experiments  where 
acid  violet  was  followed  by  crocein  orange,  since  they  show 
that  acid  violet  is  by  far  the  stronger  of  the  two  colors  on 
wool. 


Studies  in  Dyeing  and  Cleaning  765 

A  few  other  combinations  of  colors  were  then  tried  out 
according  to  the  same  general  method.  The  combinations 
were :  crocein  orange  and  acid  green,  alkali  blue  and  acid  green, 
acid  violet  and  acid  green,  brilliant  green  and  safranine. 
The  concentration  of  each  dye  with  the  exception  of  brilliant 
green  and  safranine  was  50  mg  in  50  cc  of  water.  In  the  case 
of  the  brilliant  green  and  safranine,  25  mg  of  dye  in  50  cc 
were  used.  For  the  above  combination  for  dyes,  as  for  the 
acid  violet  and  crocein  orange,  in  no  instance  was  the  first 
color  replaced  by  the  second  color.  The  resulting  color  for 
the  first  two  combinations  was  practically  the  same,  namely, 
a  brownish  black;  for  the  acid  violet  followed  by  acid  green 
a  greenish  black.  When  the  safranine  was  followed  by  the 
brilliant  green,  the  color  resulting  was  a  greenish  black;  when 
the  fiber  was  dyed  in  the  reverse  order,  the  color  resulting 
was  a  bluish  black,  thus  showing  that  the  brilliant  green 
tended  to  displace  the  safranine  more  readily  than  the  saf- 
ranine the  brilliant  green,  that  is,  the  brilliant  green  is  the 
stronger  color  on  wool.  This  is  analogous  to  the  behavior  of 
acid  violet  and  crocein  orange.  The  acid  violet  displaced  the 
crocein  orange  more  than  the  crocein  orange  did  the  acid 
violet. 

It  is  evident  from  the  above  data  that  on  wool  alone, 
one  color  cannot  be  completely  replaced  by  another  in  one 
treatment  unless,  as  in  the  case  of  acid  violet,  the  amount  of 
the  first  dye  used  is  very  small  in  comparison  to  the  amount  of 
the  second  dye  used. 

To  ascertain  whether  the  color  on  a  fiber  could  be  dis- 
placed by  successive  treatments  of  the  second  dye,  wool  was 
dyed  in  the  usual  manner  and  then  further  treated  to  fresh 
successive  baths  of  the  second  dye.  As  a  typical  case,  the 
fiber  dyed  in  acid  green  followed  by  crocein  orange  was  studied. 
The  concentration  of  the  acid  green  was  50  mg  in  50  cc.  Two 
samples  were  dyed  first  in  acid  green  and  then  each  of  these 
in  fresh  baths  of  crocein  orange  (40  mg) .  The  first  treatments 
of  the  dyed  fiber  resulted  in  a  brownish  black  color  which 
color  remained  after  the  second  treatment.  In  the  third 
treatment  an  orange  tint  of  the  fiber  was  noticeable.  In  the 


766  D.  B.  Lake 

fifth  treatment  practically  all  of  the  acid-green  color  had  been 
displaced.  Similar  experiments  were  carried  out  with  alkali 
blue  and  crocein  orange,  and  acid  violet  and  crocein  orange. 
With  respect  to  alkali  blue  and  crocein  orange  the  fiber  was 
dyed  first  in  50  mg  of  alkali  blue.  This  dyed  fiber  was  then 
treated  with  four  successive  amounts  of  crocein  orange,  namely, 
50,  25,  25  and  25  mg,  respectively.  The  resulting  color 
of  the  fiber  at  the  end  of  the  fourth  treatment  was  only  slightly 
different  from  that  at  the  end  of  the  first  treatment.  How- 
ever, a  slight  orange  tinge  of  the  fiber  was  noticeable.  Con- 
cerning the  acid  violet  and  crocein  orange  two  sets  of  fibers 
were  dyed  in  30  mg  and  40  mg  of  acid  violet,  respectively. 
These  dyed  fibers  were  then  treated  with  five  successive 
amounts  of  crocein  orange,  namely,  50,  25,  25,  25  and  25  mg 
respectively.  At  the  end  of  the  last  treatment  the  color 
of  the  fibers  did  not  seem  markedly  different  from  that  at  the 
end  of  the  first  treatment. 

From  the  above  experiments  the  conclusion  may  be  drawn 
that  it  is  very  difficult  to  mask  completely,  that  is,  displace, 
by  a  second  dye  the  color  of  the  dye  adsorbed  by  wool  fiber. 
This  would  seem  to  show  that  the  influence  of  the  dye  in  the 
bath  in  displacing  the  adsorbed  dye  is  small,  if  not  negligible. 
Furthermore,  it  would  seem  that  where  the  final  color  of  the 
dyed  fiber  tended  to  become  more  like  that  of  the  second  dye 
it  was  due,  in  part  at  least,  to  the  more  or  less  partial  masking 
of  the  color  of  the  original,  adsorbed  dye  by  the  second  dye. 

From  this  we  should  conclude  that  if  it  is  desired  to 
bring  about  a  rapid  complete  change  of  color  of  a  fiber,  dyed 
for  example  with  acid  violet,  it  would  first  be  necessary  to' 
remove  the  dye  from  the  fiber  by  means  of  a  solution  of  either 
Na2COs  or  NH4C2H3O2  before  treating  the  fiber  with  the  dye 
for  the  desired  color.1  There  are  cases  where  this  method 
would  not  be  necessary  as  shown  in  the  experiment  with  acid 
green  and  crocein  orange.  There  it  was  seen  that  the  acid 
green  was  not  held  so  tenaciously  as  was  acid  violet  or  alkali 


1  Knecht,  Rawson  and  Lowenthal:  A  Manual  of  Dyeing,  I,  217  (1910). 


Studies  in  Dyeing  and  Cleaning  767 

blue;  hence  by  successive  treatments  of  the  dyed  fiber  in 
fresh  baths  of  crocein  orange,  the  acid-green  color  should 
eventually  be  completely  displaced  by  the  crocein-orange 
color.  From  preceding  experiments  we  should  expect  this 
color  displacement  to  be  accompanied  by  a  fairly  rapid  dis- 
placement of  the  dye,  acid  green.  This  displacement  of  the  acid 
green  may  be  explained  as  due  to  the  fact  that  it  was  either 
dissolved  or  peptized  by  the  water,  or  peptized  by  the  crocein 
orange.  There  is  no  doubt  that  in  the  case  of  alkali  blue 
and  acid  violet  their  complete  displacement  could  be  brought 
about  eventually  and  for  the  same  reason. 

The  idea  that  the  displacement  of  a  dye  from  a  fiber 
may  be  accounted  for  by  assuming  that  the  first  dye  is  either 
dissolved  or  peptized  by  the  solvent  or  is  peptized  by  the 
second  dye,  leads  us  to  the  second  point  in  the  investigation, 
namely,  to  account  for  the  apparent  displacement  of  one  dye 
by  another. 

If  we  go  back  to  the  experiments  described,  we  can  con- 
sider this  evidence  of  the  displacement  of  a  dye  from  a  fiber 
by  the  appearance  of  the  final  baths  in  each  case.  In  the 
case  of  the  first  experiments  with  acid  violet  and  crocein 
orange,  where  only  a  small  amount  of  acid  violet  was  used 
for  the  first  color,  it  was  rather  difficult  to  detect  any  acid 
violet  in  the  second  final  bath.  Up  to  a  concentration  of 
20  mg  of  crocein  orange  the  final  bath  was  of  a  dark  lemon 
color.  To  the  naked  eye  there  was  no  evidence  of  acid  violet 
present.  Beyond  a  concentration  of  20  mg  of  crocein  orange 
the  color  of  the  final  bath  was  that  of  the  original  color  of 
the  crocein-orange  bath.  In  none  of  these  experiments  was 
there  any  visible  evidence  of  the  displacement  of  acid  violet. 
This  was  especially  noticeable  as  the  crocein  orange  was  ad- 
sorbed to  a  considerable  extent  by  the  dyed  fiber. 

However,  seemingly  more  positive  evidence  of  the  dis- 
placement of  acid  violet  by  crocein  orange  was  obtained 
when  the  wool  was  dyed  in  more  concentrated  solutions  of 
the  acid  violet.  For  example,  in  the  case  where  two  sets 
of  the  fiber  were  dyed  in  30  and  40  mg,  respectively,  and  then 


768  D.  B.  Lake 

treated  to  successive,  fresh  baths  of  crocein  orange  the  final 
baths  in  every  case,  even  in  the  last  treatment,  were  of  a 
wine-red  color,  thus  showing  that  in  each  final  bath  there 
was  present  unadsorbed  crocein  orange  and  some  apparently 
displaced  acid  violet.  As  in  the  case  of  the  acid  violet  and 
crocein  orange,  so  in  the  case  of  acid  green  and  crocein  orange, 
alkali  blue  and  acid  green,  and  acid  violet  and  acid  green  where 
the  fiber  was  dyed  in  a  rather  concentrated  solution  of  the 
first  dye,  the  final  baths  in  all  cases  showed  the  presence  of 
the  unadsorbed  dye  and  the  apparently  displaced  dye.  This 
was  particularly  striking  in  the  case  of  acid  green  followed 
by  crocein  orange.  In  every  treatment  of  the  dyed  fiber, 
even  to  the  last  one,  the  color  of  the  final  bath  was  of  a  "dirty" 
green  showing  that  both  dyes  were  present.  In  all  cases, 
the  apparently  displaced  dye  seemed  to  be  present  in  con- 
siderable amounts. 

Doubt  as  to  the  correctness  of  the  idea  of  the  actual  dis- 
placement of  one  dye  by  another  arose  when  the  fact  of  the 
bleeding  of  a  fiber  dyed  at  the  temperature  of  a  boiling  water- 
bath  was  taken  into  consideration.  Thus  wool  dyed  with  acid 
violet,  crocein  orange,  alkali  blue  and  acid  green,  respectively, 
was  practically  stripped  of  each  dye  by  putting  the  dyed 
fiber  in  successive  fresh  baths  of  boiling  water.  The  removal 
of  the  dye  in  each  case  was  brought  about  by  either  the  solvent 
or  peptizing  action  of  the  water.  In  accordance  with  the 
law  of  "reverse  adsorption"1  more  dye  was  removed  during 
the  first  two  or  three  treatments  than  during  the  succeeding 
treatments.  In  fact  when  the  amount  of  dye  on  the  fiber 
was  rather  small  its  removal  was  very  slow  and  difficult. 
Now  at  the  temperature  of  the  water-bath,  at  which  the  ex- 
periments described  were  carried  out,  bleeding  of  the  dyed  fiber 
likewise  readily  occurred.  This  was  shown  for  fibers  dyed  in 
acid  violet,  crocein  orange,  alkali  blue,  and  acid  green.  There- 
fore, from  these  data  it  is  seen  that  the  question  to  settle  was 


1  Hatschek:  "An  Introduction  to  the  Physics  and  Chemistry  of  Colloids," 
82  (1916). 


Studies  in  Dyeing  and  Cleaning 


769 


whether  a  dyed  fiber  would  bleed  more  in  the  presence  of  a 
second  dye  solution  than  in  pure  water  at  the  temperature 
at  which  the  experiments  had  been  carried  out. 

Briefly  the  method  used  to  answer  the  question  was  first 
to  treat  four  samples  of  the  wool  in  a  dye  bath  of  known  con- 
centration at  the  temperature  of  the  boiling  water-bath  at 
about  97°  for  forty-five  minutes;  remove;  wash;  test  two  of 
the  samples  for  bleeding  at  the  same  temperature  for  twenty- 
five  minutes  in  the  same  volume  of  water  and  dye  the  other 
two  dyed  samples  in  a  fresh  bath  of  the  second  dye  of  the 
same  concentration  as  the  first  dye  and  under  the  same  con- 
ditions. Since  the  idea  was  to  obtain  relative  information 
concerning  the  bleeding  of  the  dye  in  its  relation  to  displace- 
ment, a  volume  of  250  cc  was  used  instead  of  50  cc  as  in  the 
previous  experiments.  The  final  solutions  were  analyzed 
colorimetrically  by  means  of  a  Duboscq  colorimeter. 

The  following  data  were  obtained  for  wool,  silk,  and 
poplin  (a  cloth  made  of  silk  and  wool,  and  used  in  place  of 
the  silk-  wool  flannel)  : 


TABLE  I 
l—Undyed  Wool 

i  gram  wool,  5  mg  dye  per  250  cc 
Temperature  —  about  97  °  C 


Dye 

A 

B 

C 

Dye  adsorbed 
Milligrams 

Dye  unadsorbed 
Milligrams 

Bleeding  test.     Am't 
dye  from  dyed  fiber 
given  up  to  250  cc 
H2O  at  about  97  ° 
after  25  minutes 
Milligrams 

Crocein 
orange 
Acid 

4.26 
4-30 
4.20 

0.74 
0.70 
.0,80 

0.53 
0.58 

0-45 

green 

4-30 

0.70 

o-35 

770 


D.  B.  Lake 


II — Dyed  Wool  from  A,  not  tested  for  bleeding;  5  mg  dye  per  250 
cc  H2O;  temp,  about  97°  C 


Dye 

D 

E 

F 

Dye  adsorbed  by 
dyed  fiber 
Milligrams 

Dye  unadsorbed  by 
dyed  fiber 
Milligrams 

Dye  given  up  to 
250  cc  H2O  at 
about  97  °  by 
dyed  fiber  from 
D  during  dyeing 
Milligrams 

Crocein 
orange 
Acid 
green 

4-35 
4-50 

4-25 
4-35 

0.65 
0.50 

0-75 
0.65 

(Acid          o  .  40 
green)    0.30 
(Crocein   o  .  50 
orange)  0.50 

l—Undyed  Silk 

i  gram,  20  mg  dye  per  250  cc  H2O 
Temperature  about  97°  C 


A 

B 

C 

Bleeding  test.     Am't 

Dye 

dye  from  dyed  fiber 

Dye  adsorbed 

Dye  unadsorbed 

given  up  to  250  cc 

Milligrams 

Milligrams 

H2O  at  about  97  ° 

after  25  minutes 

Milligrams 

Crocein 

1.8 

18.2 

0.46 

orange 

1.8 

18.2 

0.23 

Acid 

9-3 

10.7 

0.88 

green 

8-7 

ii.  3 

0.79 

II — Dyed  silk  from  A,  not  treated  for  bleeding;  20  mg  dye  per  250 
cc  H2O;  temp,  about  97°  C 


D 

E 

F 

Dye  given  up  to 

Dye 

Dye  adsorbed  by 
dyed  fiber 
Milligrams 

Dye  unadsorbed  by 
dyed  fiber 
Milligrams 

25  cc  H2O  at 
about  97  °  by 
dyed  fiber  from 
D  during  dyeing 

Milligrams 

Crocein 

1.8 

18.2 

(Acid        0.70 

orange 

2.0 

18.0 

green)  0.65 

Acid 

9.0 

II  .O 

(Crocein   orange) 

green 

9.0 

II  .O 

Presence        not 

indicated    by 

method        of 

analysis 

Studies  in  Dyeing  and  Cleaning 


77* 


I — Undyed,  Poplin 

i  gram  poplin;  20  mg  dye  per  250  cc  H2O 
Temperature — about  97  °  C 


Dye 

A 

B 

C 

Dye  adsorbed 

Dye  unadsorbed 

Bleeding  test.     Am't 
dye  from  dyed  fiber 
given  up  to  250  cc 
H2O  at  about 
97°  after  25 
minutes 

Crocein 

3-1 

16.9 

I  .  I 

orange 
Acid 
green 

2.9 

5-5 
5-6 

17.1 
H-5 

14.4 

I  .  I 

2.0 
2.0 

II — Dyed  Poplin  from  A,  not  treated  for  bleeding;  20  mg  dye  per 
250  cc  H2O;  temperature  about  97°  C 


D 

E 

F 

Dye  given  up  to 

Dye 

Dye  adsorbed  by 
dyed  fiber 
Milligrams 

Dye  unadsorbed  by 
dyed  fiber 
Milligrams 

250  cc  H^O  at 
about  97  °  C  by 
dyed  fiber  from 
D  during  dyeing 

Milligrams 

Crocein 

3-0 

17.0 

(Acid           2  .  0 

orange 

3-0 

17.0 

green)    2.1 

Acid 

5-0 

15.0 

(Crocein      i  .  o 

green 

5-0 

15.0 

orange)    o  .  9 

Other  data  for  crocein  orange  and  acid  violet  were  ob- 
tained with  respect  to  wool  but  were  lost  when  Morse  Hall 
burned.  Since  acid  violet  could  not  be  obtained  in  the  market, 
experiments  with  these  two  dyes  were  not  repeated.  The 
data  in  all  respects,  however,  agreed  with  the  above  for  acid 
green  and  crocein  orange. 

The  data  seem  to  account  for  the  apparent  displace- 
ment of  one  dye  by  another.  In  all  of  the  experiments  in 
which  the  final  bath  indicated  the  presence  of  the  two  dyes, 
it  is  evident  that  the  presence  of  one  dye  is  due  to  bleeding, 


772 


D.  B.  Lake 


and  the  presence  of  the  other  dye  to  incomplete  adsorption. 
It  is  evident  also  that  the  bleeding  of  the  first  dye  is  not 
increased  as  a  result  of  the  adsorption  of  the  second  dye, 
or  is  independent  of  the  presence  of  the  second  dye.  In 
other  words  these  data  seem  to  bring  out  the  fact  that  the 
removal  of  the  dye  on  the  dyed  fiber  is  brought  about  through 
peptization  by  the  liquid  rather  than  peptization  by  the  dis- 
solved dye.  This  is  indicated  by  comparing  Columns  C  and 
F  of  the  above  tables  for  any  fiber.  Thus  in  the  case  of 
wool: 


Dye 

C 

F 

Bleeding  test.    Amount 
dye  given  up  by  dyed 
fiber  to  250  cc  H2O 
at  about  97  °  C 
after  25 
minutes 
Milligrams 

Dye  given  up  by  dyed  fiber 
to  250  cc  HaO  at  about 
97  °  C  during  dyeing 
Milligrams 

Crocein  orange 
Acid  green 

0-53 
0.58 
0.80 
0.70 

Crocein  orange      0.50 
0.50 
Acid  green              o  .  40 
0.30 

This  apparent  inactivity  of  the  dissolved  dye  is  probably 
due  to  the  fact  that  the  set  adsorbed  dye  is  "extremely  difficult" 
to  peptize  even  by  boiling  water.  This  is  shown,  for  example, 
in  the  case  of  acid  violet  3R  which  on  wool  bleeds  but  slightly 
in  boiling  water,  that  is,  is  peptized  only  slightly  by  it.  Hence 
the  conclusion  that  a  dye  in  solution  (true  or  colloidal)  possesses 
apparently  far  less  ability  to  peptize  an  adsorbed  dye  than 
does  water  and,  therefore,  the  dye  in  solution  plays  little 
part  in  the  removal  of  the  adsorbed  dye. 

Concerning  the  final  color  of  a  fiber,  especially  with  re- 
gard to  wool,  complete  change  takes  place  only  when  the 
amount  of  the  dye  adsorbed  is  rather  small  and  the  amount 
of  second  dye  adsorbed  is  relatively  large;  in  other  words, 
when  the  amount  of  the  first  dye  adsorbed  is  so  small  that 


Studies  in  Dyeing  and  Cleaning  773 

the  color  of  the  second  dye  is  able  to  mask  it  completely. 
This  is  illustrated  in  the  case  where  only  0.25  mg  of  acid 
violet,  adsorbed  as  the  first  dye,  was  completely  masked 
by  crocein  orange.  In  any  case  where  a  large  amount  of  the 
first  dye  has  been  adsorbed,  the  color  replacement  goes  hand 
in  hand  with  its  actual  displacement  from  the  fiber,  which 
displacement  seems  to  be  entirely  independent  of  the  pres- 
ence of  the  second  dye. 

With  regard  to  silk  we  have  a  complete  replacement  of 
one  color  by  another  as  for  wool.  This  is  illustrated  in  the 
displacement  of  crocein- orange  color  by  acid-green  color. 
The  amount  of  crocein  orange  adsorbed  was  comparatively 
small;  and  hence  when  this  dyed  fiber  was  treated  to  a  fresh 
bath  of  acid  green  at  the  temperature  of  the  boiling  water- 
bath,  with  the  result  that  considerable  bleeding  of  the  crocein 
orange  took  place,  the  amount  of  crocein  orange  left  on  the 
fiber  was  so  small  that  its  color  was  easily  masked  by  that 
of  the  acid  green.  Thioflavine  T  on  silk  followed  by  safranine 
affords  an  instance  in  which  the  color  of  one  dye  is  displaced 
by  another,  and  yet  in  which  large  amounts  of  the  first  dye 
are  taken  up.  A  one-gram  sample  of  silk  dyed  in  25  mg  of 
each  dye  per  250  cc  H2O  at  about  97°  C  adsorbed  about  80 
percent  of  each,  respectively.  Notwithstanding  that  rela- 
tively large  amounts  of  thioflavine  T  were  adsorbed  its  color 
was  easily  masked  by  the  safranine.  It  is  obvious  that 
the  amount  of  thioflavine  T  given  up  to  the  safranine  solu- 
tion was  not  sufficient  to  account  for  the  displacement  of 
the  thioflavine  T  color  by  the  safranine  color,  as  in  the  case 
of  crocein  orange  followed  by  acid  green.  The  probable 
reason  for  the  masking  of  the  thioflavine  color  is  due  to  the 
fact  that  it  is  of  very  light  shade,  thus  making  its  displace- 
ment or  masking  comparatively  easy  by  a  darker  one  as 
safranine.  It  should  be  pointed  out  that  safranine  color  was 
not  replaced  by  the  thioflavine  T  color  in  one  treatment. 

Summing  up  then  the  results  of  the  experiments,  we  con- 
clude that  we  may  speak  of  the  displacement,  or  preferably 
the  masking,  of  one  color  by  another  under  suitable  conditions. 


774  D-  B-  Lake 

This  masking  of  one  color  by  another  is  accompanied  by  a 
partial  displacement  of  the  dye  from  the  fiber.  But  this  dis- 
placement does  not  seem  to  be  brought  about  by  the  presence 
of  the  second  dye  but  by  the  solvent  or  peptizing  action  of 
the  solvent. 

The  above  experiments  were  carried  on  at  the  tempera- 
ture of  the  boiling  water-bath.  Since,  at  this  temperature 
under  ordinary  conditions,  there  was  no  complete  replacement 
of  one  color  by  another  on  wool,  a  few  experiments  were  carried 
out  at  room  temperature  to  ascertain  whether  dyes  behaved 
similarly  at  that  temperature.  In  all  of  these  experiments 
the  wool,  used  as  bought,  was  entered  in  the  first  dye  bath 
containing  25  mg  of  dye  per  50  cc  H^O  for  36  hours;  after 
which  it  was  removed,  washed  in  distilled  water,  and  then 
entered  in  the  second  dye  bath  of  the  same  concentration,  for 
the  same  length  of  time.  The  following  pairs  of  dyes  were 
studied:  acid  violet  3R  and  crocein  orange  R,  cyanol  green 
and  brilliant  scarlet,  safranine  and  brilliant  green,  thio- 
flavine  T  and  safranine,  cyanol  green  and  lanafuchsine, 
brilliant  green  and  thioflavine  T. 

Acid  violet  at  room  temperature  is  adsorbed  very  slightly 
by  wool.  Crocein  orange,  on  the  other  hand,  is  adsorbed 
strongly,  hence  it  readily  displaced  the  acid  violet  color  from 
the  fiber.  Crocein  orange  color,  on  the  other  hand,  was  in 
no  way  displaced  by  acid  violet.  The  color  of  cyanol  green 
was  completely  displaced  by  brilliant  scarlet,  although  brilliant 
scarlet  followed  by  cyanol  green  was  not  so  completely 
displaced.  The  second  final  baths  in  each  case  contained 
both  dyes.  Safranine,  followed  by  brilliant  green,  gave  a 
dark-colored  fiber,  the  color  of  the  safranine  predominating. 
Brilliant  green,  followed  by  safranine,  likewise  gave  a  dark- 
colored  fiber,  the  brilliant  green  predominating.  The  fiber 
dyed  in  emerald-green  followed  by  safranine  took  on  a  slightly 
greenish  tinge,  while  in  the  reverse  procedure  the  safranine 
color  predominated  on  the  fiber.  In  all  of  these  cases  the 
second  final  baths  showed  both  dyes  to  be  present.  Thio- 
flavine T  followed  by  safranine  was  completely  replaced  by 


Studies  in  Dyeing  and  Cleaning  775 

the  safranine.  Thioflavine  T  was  present  in  the  second  final 
bath.  Safranine  was  not  replaced  at  all,  so  far  as  the  color 
of  the  fiber  was  concerned,  by  thioflavine  T,  although  in 
the  final  bath  safranine  was  present.  Cyanol  green  followed 
by  lanafuchsine  gave  a  slate-blue  color  to  the  fiber,  as  well 
as  did  lanafuchsine  followed  by  cyanol  green.  The  final 
baths  in  both  cases  contained  the  two  colors.  Brilliant 
green  followed  by  thioflavine  T  retained  its  color  on  the  fiber, 
while  thioflavine  T  was  completely  replaced  by  brilliant  green. 
In  this  latter  case,  I  could  see  no  evidence  of  thioflavine  T 
in  the  final  bath. 

The  results  of  these  experiments  at  room  temperature  are 
similar  to  those  carried  on  at  the  higher  temperature.  They  are 
purely  qualitative,  although  there  is  no  reason  for  assuming 
that  quantitative  data  as  to  the  principles  involved  would  not 
agree  with  the  data  obtained  for  the  higher  temperature.  At 
the  lower  temperature  there  seemed  to  be,  on  the  whole,  a  more 
complete  replacement  of  one  color  by  another,  and  a  more  com- 
plete apparent  removal  of  the  first  dye  by  the  second.  This 
latter  phenomenon  may  be  accounted  for  by  postulating  that  at 
the  higher  temperature  the  dye  is  more  completely  "set"  on 
the  fiber  and  hence  does  not  bleed  so  readily  even  at  that 
temperature.  It  was  very  noticeable  that  the  bleeding  of 
fibers  dyed  at  room  temperature  was  far  greater  at  that 
temperature  than  fibers  dyed  at  about  100°  and  tested  for 
bleeding  at  that  temperature.  At  the  lower  temperature  two 
cases  were  brought  out  where  one  color  practically  replaced 
the  other  completely ;  namely,  thioflavine  T  by  safranine  and 
thioflavine  T  by  brilliant  green.  With  respect  to  thioflavine 
T  followed  by  safranine,  both  dyes  were  present  in  the  second 
final  bath.  In  the  case  of  thioflavine  T  followed  by  brilliant 
green  it  was  rather  difficult  to  detect  the  presence  of  thio- 
flavine T  in  the  second  final  bath.  In  fact,  with  the  naked 
eye,  no  evidence  of  thioflavine  T  could  be  seen. 

An  interesting  experiment  showing  how  one  color  will 
predominate  at  one  temperature,  and  the  other  at  a  higher 
temperature  was  brought  out  in  the  case  of  acid  violet  and 


776  D.  B.  Lake 

crocein  orange.  A  one-gram  sample  of  wool  in  5  mg  of  cro- 
cein  orange  and  45  mg  of  acid  violet  per  50  cc  H2O  was  dyed 
at  room  temperature  for  72  hours;  another  sample  in  a  bath 
of  the  same  concentration  of  the  dyes  at  the  temperature 
of  the  boiling  water-bath.  At  room  temperature  the  fiber 
was  dyed  a  pure  crocein-orange  color,  while  at  the  higher 
temperature  it  was  dyed  largely  the  color  of  the  acid  violet. 
This  experiment  illustrated  selective  adsorption  very  finely, 
especially  at  the  lower  temperature.  As  showing  more 
strikingly  this  selective  adsorption  at  room  temperature 
in  the  case  of  these  two  dyes  a  one-gram  sample  of  wool  was 
entered  in  a  volume  of  50  cc  containing  10  mg  orange  and  1000 
mg  acid  violet  and  left  in  this  bath  24  hours.  At  the  end  of 
that  time  the  fiber  was  dyed  a  fairly  pure  color  of  crocein 
orange.  There  was  no  evidence  of  the  adsorption  of  any  acid 
violet. 

In  the  experiments  described  there  is  one  fact  that  stands 
out  quite  prominently,  namely,  that  a  dyed  fiber,  under 
suitable  conditions,  will  bleed;  that  is,  if  placed  in  water 
under  suitable  conditions  it  will  lose  some  of  its  dye  to  the 
water.  This  bleeding  will  continue  until,  for  the  particular 
volume  of  water,  equilibrium  is  reached  between  the  dye 
in  the  solution  and  the  dye  on  the  fiber.  As  has  already 
been  pointed  out,  if  one  set  of  fibers  is  dyed  at  room  tem- 
perature, and  another  set  at  a  higher  temperature,  for  example, 
the  temperature  of  a  boiling  water-bath,  the  fiber  dyed  at  the 
higher  temperature  will  bleed  less,  even  when  tested  for  bleed- 
ing at  the  higher  temperature,  than  the  fiber  dyed  at  room 
temperature  and  tested  for  bleeding  at  the  lower  temperature. 
In  fact  a  fiber  dyed  at  a  high  temperature  as  mentioned  above 
will  not  bleed  at  all  at  room  temperature.  This  difference  in 
bleeding,  depending  on  the  temperature  of  dyeing,  is  probably 
due  to  the  fact  that  the  dye  adsorbed  at  the  higer  tempera- 
ture is  coagulated  on  the  fiber,  or,  as  is  popularly  known  "set" 
on  the  fiber,  with  the  result  that  bleeding  is  more  or  less  pre- 
vented. These  general  observations  concerning  bleeding  led  to 
a  study  of  the  conditions  involving  the  dyeing  of  a  fiber,  or 


Studies  in  Dyeing  and  Cleaning 


777 


the  treatment  of  a  dyed  fiber,  that  would  lead  to  a  minimum  of 
bleeding  when  the  dyed  fiber  is  exposed  to  practically  boiling 
water. 

The  first  experiment  was  concerned  with  the  relation  be- 
tween the  length  of  time  of  dyeing  at  high  temperature  and 
bleeding.  "The  real  object  of  heating  is  to  coagulate  or 
agglomerate  the  dye,  thus  making  it  less  soluble."1  Hence 
the  conclusion  that  prolonged  dyeing  at  a  high  temperature 
should  practically  prevent  bleeding.  The  dyeing  was  carried 
on  at  the  temperature  of  the  boiling  water-bath.  Samples  of 
wool,  one  gram  each,  were  entered  in  a  dye  bath  of  40  mg  per 
250  cc  H2O.  The  time  of  dyeing  varied  from  one  to  three 
hours.  The  dye  used  was  acid  violet. 

The  test  for  bleeding  was  carried  out  as  follows:  The 
washed  dyed  fiber  was  put  in  a  beaker  containing  250  cc  of 
water  and  the  whole  heated  to  the  temperature  of  the  water- 
bath  for  one-half  hour. 

The  dye  unadsorbed  and  bled  was  determined  colori- 
metrically.  The  data  following  are  the  average  of  duplicate 
experiments : 

TABLE  II 


Bleeding  test.     Am't 

Time 

Dye  adsorbed 

Dye  unad- 
sorbed 

dye  given  up  to 
250  cc  H2O  at 
about  97  °  C 

after  30  minutes 

i  hour 

37  mg 

3  mg 

about  0.30  mg 

i  Y2  hours 

39  mg 

i  mg 

about  0.80  mg 

3  hours 

38.5  mg 

i-5  mg 

about  0.60  mg 

These  data  indicate  that  prolonged  dyeing  at  practically 
the  temperature  of  boiling  water  does  not  cut  down  the  amount 
of  dye  that  will  bleed  from  a  fiber.  This  may  be  accounted 
for  by  assuming  that  equilibrium  between  the  adsorbed  and 
unadsorbed  dye  was  reached  at  the  end  of  one  and  one-half 
hours,  hence  the  dyeing  beyond  that  time  was  of  no  avail. 


1  Bancroft:  Jour.  Phys.  Chem.,  19,  145  (1915). 


778 


D.  B.  Lake 


In  practical  work,  especially  with  acid  dyes,  dyeing  is 
carried  on  in  so-called  acid  baths,  that  is,  baths  to  which  a 
certain  amount  of  hydrochloric  acid  or,  preferably,  sulphuric 
acid  is  added.  It  is  generally  accepted  that  the  presence  of 
these  acids  brings  about  a  better  "setting"  of  the  dye  and 
hence  makes  it  faster  to  washing  or  bleeding.  With  this  idea 
in  mind,  experiments  were  carried  out  with  acid  violet  in  the 
presence  of  hydrochloric  acid  and  sulphuric  acid.  The  con- 
ditions of  dyeing  were  the  same  as  in  the  preceding  experi- 
ment. Forty  milligrams  of  dye  were  used  and  the  amount 
of  acids  3  percent  by  weight  of  the  wool. 

The  data,  the  average  of  duplicate   experiments,   follow: 

TABLE  III 


Dye  bled.     Am't 

Time 

Acid  used 
3%  by 
weight  of 
wool 

Dye  adsorbed 
Milligrams 

Dye  unad- 
sorbed 
Milligrams 

dye  given  up  by 
dyed  fiber  to  250  cc 
H2O  at  about  97  ° 
after  30  minutes 

Milligrams 

i  hour 

H2S04 

39-83 

0.17 

O.  IO 

i  Y2  hours 

H2SO4 

39-70 

0.30 

0.20 

3  hours 

H2S04 

39-70 

0.30 

0.20 

3  hours 

HC1 

39-70 

0.30 

O.2O 

Thus,  as  indicated  above,  these  data  bring  out  the  fact 
that  a  fiber  such  as  wool  dyed  with  an  acid  dye  in  an  acid 
bath  gives  up  less  dye  to  practically  boiling  water  than  it 
does  when  dyed  with  the  same  dye  in  a  neutral  bath.  (See 
immediately  preceding  table.)  The  most  probable  reason 
for  this  is  that  the  acid  aids  in  coagulating  or  setting  the  dye 
on  the  fiber,  thus  making  it  less  soluble;  hence  less  dye  is  ex- 
tracted by  hot  water,  or  the  dye  bleeds  less  readily. 

It  was  observed  in  the  above  experiments  that  the  fiber 
adsorbed  the  dye  much  faster  in  the  acid  bath  than  in  the 
neutral  bath.  This  was  to  be  expected  as  postulated  by 
Bancroft.1 

Experiments  were  next  carried  out  in  which  wool  was 


Jour.  Phys.  Chem.,  18,  4  (1914). 


Studies  in  Dyeing  and  Cleaning  779 

% 

dyed  in  neutral  and  acid  baths  as  usual,  but  before  test- 
ing for  bleeding  it  was  subjected  to  heating  in  a  hot-air  oven 
at  a  temperature  of  io5°-no°  C  for  one  hour.  The  acids 
used  were  hydrochloric  and  sulphuric.  Negative  results 
were  obtained  in  all  cases;  that  is,  after  this  heating  the 
dyed  fiber  bled  as  much  as  the  fiber  which  had  not  been  sub- 
jected to  this  extra  heating. 

In  the  above  experiments  the  temperature  of  dyeing  was 
about  96°-97°  C. 

It  was  hoped  that  by  dyeing  in  an  atmosphere  of  "live" 
steam  the  dye  would  be  fixed  more  firmly  on  the  fiber,  so 
that  it  would  be  faster  to  washing.  Accordingly,  an  apparatus 
was  arranged  by  which  live  steam  was  allowed  to  bubble 
through  a  solution  of  dye  contained  in  an  Erlenmeyer  flask. 
The  Erlenmeyer  flask  was  partially  immersed  in  boiling  water. 
Before  the  passage  of  the  steam  the  fiber  was  thoroughly  wet 
with  the  dye  solution.  The  dye  used  was  acid  violet  and  the 
amount  40  mg  per  50  cc  of  water.  The  dyeing  was  carried  on 
for  one  hour.  Duplicate  experiments  were  performed  in 
neutral  and  acid  (HC1)  baths. 

In  the  first  set  of  experiments  after  the  dyeing  in  live 
steam  the  fibers  were  put  at  once  into  distilled  water  and 
tested  for  bleeding  as  usual  at  97°.  The  bleeding  was  no 
less  than  in  the  case  carried  on  at  96°  to  97°.  The  fibers 
dyed  in  the  neutral  baths  bled  slightly  more  than  those 
dyed  in  the  acid  bath.  An  experiment  in  which  the  fibers, 
dyed  as  above,  were  subjected  to  live  steam  for  one-half 
hour  before  testing  for  bleeding  in  the  usual  manner  like- 
wise gave  negative  results;  that  is,  the  bleeding  by  this 
treatment  was  not  cut  down  any.  The  fibers  dyed  in  the 
acid  bath  bled  considerably  less  than  those  dyed  in  the  neu- 
tral bath.  Another  set  of  fibers  was  subjected  to  the  live 
steam  for  1/z  hour,  and  tested  for  bleeding  by  immersing  in 
water  through  which  live  steam  bubbled  for  one  hour.  Here 
profuse  bleeding  took  place.  The  fibers  dyed  in  the  neutral 
and  acid  baths  bled  about  equally.  The  container  in  both 
experiments  was  immersed  in  boiling  water. 


780  D.  B.  Lake 

At  first  thought  it  seems  strange  that  at  the  tempera- 
ture of  the  live  steam  the  dye  was  not  fixed  more  firmly  on 
the  fiber,  as  shown  when  tested  for  bleeding  at  the  tempera- 
ture of  the  boiling  water-bath.  However,  the  explanation  is 
similar  to  that  advanced  to  account  for  the  greater  bleed- 
ing of  the  fiber  dyed  in  a  neutral  bath  as  compared  to  its 
bleeding  when  dyed  in  an  acid  bath.  At  the  temperature  of 
the  ''live"  steam  the  dye  was  fixed  no  more  firmly  on  the 
fiber  than  at  the  lower  temperature.  Hence  the  fiber  gave 
up  as  much  color  to  the  hot  water  as  to  the  one  dyed  at  the 
lower  temperature. 

With  reference  to  the  bleeding  of  the  dyed  fiber  at  the 
temperature  of  "live"  steam  the  data  brought  out  the  fact 
that  it  was  profuse.  This  profuse  bleeding  can  be  explained, 
however,  by  assuming  that  at  this  high  temperature  the  dye 
on  the  fiber  was  quite  readily  peptized.1  Hence  a  larger 
amount  of  color  was  given  up  to  the  water  than  would  ordi- 
narily have  been  the  case. 

In  dyeing  at  the  temperature  of  live  steam  it  was  found  that 
in  all  cases  not  so  much  dye  was  taken  up  by  the  fiber  at  this 
temperature,  as  was  taken  up  at  96  °-gj  °  C,  which  was  from  3  to 
5  percent  less.  This  is  in  harmony  with  data  published  by  Mills 
and  Rennie,2  and  Brown.3  Mills  and  Rennie  found  that  wool 
dyed  with  rosaniline  acetate  adsorbed  a  maximum  amount  at 
31  °  and  practically  none  at  81  °.  The  experiments  were  run  for 
one  hour  at  the  temperature — 1.46°  +  1.50,  6.25°,  and  at  suc- 
cessive ten  degree  intervals  to  80.25°,  respectively.  The 
amount  of  dye  left  in  the  bath  at  the  end  of  one  hour  was  de- 
termined colorimetrically.  Brown's  method  of  experimenta- 
tion was  similar  to  that  of  Mills  and  Rennie.  He  studied  the 
adsorption  of  acid  and  basic  dyes  by  the  wool.  The  figures 
in  the  subjoined  table  are  from  his  data,  and  are  the  per- 
centages of  the  dye  left  in  the  solution.  The  first  three  dyes 
are  acid  dyes,  the  last  three  basic  dyes. 


1  Bancroft:  Jour.  Phys.  Chem.,  20,  85  (1916). 

-  Jour.  Soc.  Chem.  Ind.,  3,  215  (1884). 

3  Jour.  Soc.  Dyers  and  Colourists,  17,  92  (1901). 


Studies  in  Dyeing  and  Cleaning 


781 


Dye 

20°  C 

4o°C 

60°  C 

80°  C 

100°  C 

Acid  magenta 

79 

H 

4 

4-3 

5-6 

Acid  green 

79 

28 

4 

4.6 

5-2 

Acid  violet  4  B  W 

44 

26 

20.8 

20.8 

28.7 

Chrysoidine  FF 

28.2 

32 

36 

46.5 

46.0 

Methylene  blue 

29.2 

24.4 

28.6 

33-i 

57-1 

Methyl  violet  B 

37-o 

7.0 

5-3 

4-7 

6.2 

With  the  exception  of  the  data  of  the  methylene  blue 
these  data  bring  out  the  fact  that  from  60°  onward  the  amount 
of  dye  adsorbed  per  unit  of  time  decreased  with  rise  of  tem- 
perature. This  can  be  accounted  for  by  assuming  that  with 
the  rise  in  temperature  the  peptizing  action  of  the  water  to- 
ward the  adsorbed  dye  increased,  thus  cutting  down  the  amount 
of  dye  adsorbed.  With  the  exception  of  chrysoidine  FF  it 
is  seen  that  up  to  the  temperature  of  60°  with  the  rise  in 
temperature  there  is  an  increase  in  the  amount  of  dye  ad- 
sorbed. This  increase,  however,  is  more  apparent  than 
real  for  notably  under  the  conditions  of  Brown's  experi- 
ments time  was  not  allowed  for  a  complete  adsorption  of 
the  dye,  especially  at  20°,  that  is,  time  was  not  allowed  for 
the  adsorption  equilibrium  to  be  reached.  At  60°  and  higher 
one  hour's  time  was,  to  all  intents  and  purposes,  sufficient 
to  bring  about  a  practically  complete  adsorption  of  the  dye; 
but  at  the  lower  temperatures  this  was  not  true.  Hence  it 
would  seem  that  if  at  the  lower  temperatures  the  wool  had 
been  left  in  the  bath  till  equilibrium  had  been  reached  the 
amount  of  dye  adsorbed  probably  would  have  equalled  the 
amount  adsorbed  at  60°,  and  even  might  have  exceeded  it. 
This  assumption  seems  to  hold  for  chrysoidine  FF  where 
it  is  seen  that  the  amount  of  dye  adsorbed  up  to  80°  de- 
creased with  the  rise  in  temperature.  At  20°  it  is  assumed 
that  the  adsorption  equilibrium  was  reached  at  the  end  of 
one  hour.  Experiments  carried  on  in  the  latter  part  of  Octo- 
ber, but  with  an  entirely  different  object  in  view,  further 
confirm  the  idea  that  at  room  temperature  the  amount  of  dye 
adsorbed  is  rather  large  in  many  cases.  One-gram  samples 


782  D.  B.  Lake 

of  wool  were  left  in  their  respective  dye  baths  for  48  hours. 
The  baths  contained  25  mg  dye  per  50  cc  water.  The  dye 
left  in  the  bath  was  determined  colorimetrically.  The  figures 
in  the  subjoined  table  refer  to  the  percentage  of  dye  left  in 
the  bath. 


Dye 

Percentage  dye 

left  in  bath 

Thioflavine  T 
Acid  green 
Brilliant  green 
Emerald-green 
Lanafuchsine 
Brilliant  scarlet 

18 
36 

20 
20 

54 
60 

Without  doubt  had  the  fibers  been  allowed  to  remain  in 
their  respective  baths  for  a  longer  period  of  time  a  greater 
adsorption  of  dye  would  have  resulted  in  each  case.  Es- 
pecially would  this  be  expected  of  lanafuchsine  and  brilliant 
scarlet. 

At  this  point  it  was  thought  advisable  to  test  a  few  more 
acid  dyes  to  see  how  far  the  general  results  obtained  for 
acid  violet  would  hold.  The  other  dyes  used  were:  acid 
green  BBN,  crocein  orange  R,  and  crystal  ponceau.  The 
acids  used  were  HC1,  H2SO4  and  H3PO4.  Two  points  were 
kept  in  view  in  these  experiments;  first  to  show  the  rela- 
tion of  "bleeding"  to  the  kind  of  treatment,  that  is,  to 
ascertain  whether  in  neutral  or  acid  dyeing  bleeding  was 
greater  or  less;  and  secondly,  to  study  the  adsorption  of 
these  acid  dyes  on  wool  in  the  presence  of  these  acids.  From 
the  point  of  view  of  the  adsorption  of  the  dye,  the  data  given 
above  for  acid  violet  in  which  dyeing  was  done  in  hydrochloric 
acid  and  sulphuric  acid  baths,  when  equivalent  amounts  of 
the  two  acids  were  used,  show  that  the  fiber  immersed  in  a 
sulphuric  acid  bath  adsorbed  as  much  dye  as  did  the  fiber 
immersed  in  the  hydrochloric  acid  bath.  This  is  not  in  ac- 
cordance with  the  theory  of  dyeing  as  postulated  by  Bancroft, 
for  according  to  that  theory  any  acid  dye  in  the  presence  of 
a  readily  adsorbed  anion,  either  from  an  acid  or  neutral  salt, 


Studies  in  Dyeing  and  Cleaning  783 

should  be  less  readily  adsorbed  than  in  the  presence  of  an 
anion  not  so  readily  adsorbed  by  the  fiber.1  In  the  case  of 
HC1  and  H2SO4,  the  sulphate  ion  is  much  more  readily  adsorbed 
by  wool  than  the  chloride  ion,  hence  a  fiber  dyed  in  the  pres- 
ence of  H2SO4  should  take  up  less  acid  dye  than  a  fiber  dyed 
in  the  presence  of  an  equivalent  amount  of  HC1.  The  data 
above  do  not  confirm  this. 

In  this  new  series  of  experiments  acid  violet  was  in- 
cluded, for  the  concentration  of  the  dye  used  and  the  method 
of  heating  were  changed,  and  it  was  thought  desirable  to  get 
comparable  data  for  all  dyes.  The  fiber,  one  gram  of  wool, 
was  entered  in  250  cc  of  dye  solution  containing  40  mg  of 
the  respective  dye.  The  dyeing  was  carried  on  at  the  boiling 
temperature  for  a  period  of  one  hour.  Preliminary  experi- 
ments had  shown  that  at  the  temperature  of  boiling  water 
practically  complete  adsorption  of  the  dyes  was  brought 
about  at  the  end  of  45  minutes.  The  fibers  were  then  tested 
for  bleeding  in  a  volume  of  250  cc  H2O  at  the  same  tempera- 
ture for  20  minutes.  The  amount  of  each  acid  used  was  10 
cc  of  N/io  strength.  The  data,  the  average  of  duplicate  ex- 
periments, follow: 

These  data  bring  out  facts  similar  to  those  obtained 
above  for  the  wool  dyed  in  neutral  and  acid  baths  of  acid 
violet.  Here  as  there  in  the  bleeding  test  fibers  dyed  in  acid 
baths  gave  up  less  color  to  the  water  than  those  dyed  in  neu- 
tral baths.  This  is  as  should  be  expected  as  pointed  out  above. 
The  data  show  also  that  the  fibers  dyed  in  acid  baths  adsorbed 
more  dye  than  those  dyed  in  neutral  baths.  Furthermore, 
if  we  compare  the  data  of  the  acid  violet  and  crystal  ponceau 
as  a  whole,  it  is  seen  that  both  dyes  gave  up  about  the  same 
amount  of  color  to  the  water  in  the  test  for  bleeding.  This  can 
be  accounted  for  by  assuming  that  during  the  dyeing  both  dyes 
were  about  equally  set.  In  general  this  comparison  of  crystal 
ponceau  and  acid  violet  holds  also  for  crocein  orange  and  acid 
green  where  for  each  dye  under  the  same  conditions  there  was 


1  Bancroft:  Jour.  Phys.  Chem.,  18,  4  (1914). 


D.  B.  Lake 


TABLE  IV 

Temperature — 100°  C 
40  mg  dye  per  250  cc  H2O 
Time — i  hour 


Bleeding  test. 

Amount  dye  given 

Acid  used 

Dye  ad- 

Dye un- 

up  by  dyed  fiber 

Dye 

10  CC  Of 

each  N/io 

sorbed 
Milli- 

adsorbed 
Milli- 

to 250  cc  H2O  at 
boiling  tempera- 

acid 

grams 

grams 

ture  for  20 

minutes 

Milligrams 

Acid  violet 

No  acid 

38.0 

2.0 

I  .0 

HC1 

39-2 

0.8 

0.4 

H2S04 

39-2 

0.8 

0.4 

H3P04 

39-1 

0.9 

0.6 

Crocein  orange 

No  acid 

32.5 

7-5 

5-0 

HC1 

38.0 

2.0 

4-4 

H2SO4 

35-5 

4-5 

3-1 

H3P04 

35-5 

4-5 

3-7 

Acid  green 

No  acid 

30.1          9.9 

3-9 

HC1 

37-5 

2-5 

2.7 

H2S04 

36.3          3-7 

2.7 

H3P04 

36.0          4.0 

3-3 

Crystal  ponceau 

No  acid 

37-7          2.3 

i-3 

HC1 

39.8          0.2 

0-5 

H2SO4 

39-4          0.6 

0.6 

H3P04 

39-4          0.6 

0.6 

the  same  amount  of  bleeding.  A  comparison  of  the  data  of 
the  acid  violet  with  crocein  orange  or  acid  green  brings  out 
strikingly  the  relation  between  the  setting  and  the  subsequent 
bleeding  of  the  dye.  According  to  the  theory  postulated 
the  acid  violet  was  more  firmly  set  on  the  wool  than  the  cro- 
cein orange  as  the  data  show  in  all  cases  the  amount  of  acid 
violet  given  up  to  the  water  during  the  bleeding  test  was  much 
less  than  the  amount  of  crocein  orange.  Finally  a  comparison 
of  the  effect  of  the  acids,  among  themselves,  on  the  adsorbed 
dyes  does  not  seem  to  bring  out  any  of  the  above  general  re- 
lationships. There  were  apparently  disturbing  factors  that 
entered  in  that  offset  the  effect  of  each  acid.  However,  if 
we  turn  to  Table  VI  which  contains  the  data  for  experiments 
carried  on  exactly  like  those  whose  data  are  recorded  in  Table 


Studies  in  Dyeing  and  Cleaning  785 

IV,  except  that  a  larger  amount  of  dye  was  used,  it  is  seen 
that  on  the  whole  an  acid  dye  adsorbed  in  a  hydrochloric 
acid  bath  seemed  to  be  more  firmly  coagulated  on  the  fiber, 
or  made  less  soluble  in  water,  than  a  dye  adsorbed  in  a  sulphuric 
acid  bath;  and  that  a  dye  adsorbed  in  a  sulphuric  acid  bath 
was  more  firmly  coagulated  on  the  fiber  than  one  adsorbed 
in  a  phosphoric  acid  bath. 

Another  interesting  point  concerning  these  data  in  addi- 
tion to  those  above  is  that  the  sulphuric  and  phosphoric  acids 
are  equally  efficient  in  bringing  about  the  adsorption  of  the 
dyes.  This  seems  strange  for  in  the  case  of  crystal  ponceau 
data  have  been  published  showing1  that  when  fibers  were 
dyed  in  baths  containing  equivalent  amounts  of  hydrochloric, 
phosphoric,  and  sulphuric  acids,  respectively,  the  greatest 
adsorption  of  dye  occurred  in  the  hydrochloric  acid  bath,  a 
less  adsorption  in  the  sulphuric  acid  bath,  and  the  least  ad- 
sorption in  the  phosphoric  acid  bath.  Since,  according  to 
the  theory  of  dyeing,1  a  readily  adsorbed  anion  will  decrease 
the  amount  of  acid  dye  taken  up  it  can  be  seen  why  wool 
dyed  in  a  sulphuric  acid  bath  should  adsorb  more  dye  than 
when  dyed  in  a  phosphoric  acid  bath.  In  the  case  of  these 
acids  the  anions  of  each  are  readily  adsorbed  by  the  wool, 
but  the  phosphate  anion  is  more  readily  adsorbed  than  the 
sulphate  anion,  hence  the  wool  dyed  in  a  phosphoric  acid  bath 
will  take  up  less  dye  than  wlien  dyed  in  a  sulphuric  acid  bath 
of  equivalent  strength.  Now  it  is  to  be  observed  from  the 
above  data  that  the  concentration  of  dye  used  was  nearly 
equal  to  the  amount  which  in  practical  language  the  fiber 
would  "about  clean  up"  even  in  neutral  baths.  This  fact 
then  leads  to  the  conclusion  that  when  a  fiber  as  wool  is  dyed, 
as  described  above,  the  "cutting  down  effect"  of  the  adsorbed 
anion  is  practically  overcome  for  probably  the  capacity  of 
the  fiber  to  adsorb  more  dye  or  sulphate  and  phosphate  ions 
is  still  very  high.  Hence  under  such  conditions  wool  takes 
up  as  much  acid  dye  from  a  phosphoric  acid  bath  as  from  a 
sulphuric  acid  bath. 

1  Bancroft:  Jour.  Phys.  Chem.,  18,  4  (1914). 


786 


D.  B.  Lake 


In  order  to  show  that  the  amount  of  phosphoric  acid  used 
is  not  so  efficient  as  an  equivalent  amount  of  sulphuric  acid 
in  bringing  about  adsorption  of  acid  dyes,  or  what  is  the  same 
thing,  that  in  the  presence  of  practically  equivalent  amounts 
of  adsorbed  hydrogen  ion  the  adsorbed  phosphate  ion  cuts  down 
the  amount  of  dye  adsorbed  more  than  the  adsorbed  sulphate 
ion  two  methods  of  experimentation  are  open:  (i)  to  the  same 
concentration  of  dye  and  acid  as  in  the  previous  experiments 
add  a  neutral  salt  with  a  common  anion ;  (2)  to  the  same  amount 
of  acids  as  above  add  a  larger  amount  of  dye  per  250  cc  H2O. 
In  the  first  method  as  mentioned,  the  same  concentration 
of  dye  and  acid  were  used  as  in  the  above  experiments.  The 
method  of  dyeing  also  was  the  same.  To  the  hydrochloric  acid 
bath  10  cc  of  N/i  NaCl  were  added;  to  the  sulphuric  acid 
bath  10  cc  N/i  Na2SO4;  to  the  phosphoric  acid  bath  10  cc 
N/ 1  Na2HPO4.  The  dyes  acid  violet  and  crocein  orange  only 
were  studied.  The  data  are  the  average  of  duplicate  experi- 
ments. 

TABLE;  V 

Temperature — 100°  C 

40  mg  dye  per  250  cc  H2O 

Time — i  hour 


Acid  dye  used 

Acid  used 
10  cc.    , 
N/io 
acid 

Salt  used 
10  cc  N/i 
neutral 
salt 

Dye  ad- 
sorbed 
Milligrams 

Dye  unad- 
sorbed 
Milligrams 

Acid  violet 

HC1 

NaCl 

39-5 

0-5 

H2S04 

Na2SO4 

36.8 

3-2 

H3P04 

Na2HP04 

I  .0 

39-0 

Crocein  orange 

HC1 

NaCl 

33-4 

6.6 

H2S04 

Na2SO4 

20.  o 

20.  o 

H3P04          Na2HP04 

O.  I 

39-9 

These  data  bring  out  rather  strikingly  the  fact  that  the 
chloride,  sulphate,  and  phosphate  ions  cut  down  the  adsorp- 
tion of  an  acid  dye,  even  when  the  concentration  of  dye  used 
is  about  what  the  fiber  will  "easily  clean  up."  The  order  in 
which  the  salts  cut  down  the  adsorption  of  the  dye  the  least, 
namely,  Na2HPO4,  NaSO4  and  NaCl  is  exactly  what  one 


Studies  in  Dyeing  and  Cleaning 


787 


would  expect  on  the  basis  that  the  phosphate  ion  is  adsorbed 
the  most,  and  the  chloride  ion  the  least.  These  readily 
adsorbed  anions  not  only  offset  the  effect  of  the  hydrogen  ion, 
but  also  counterbalanced  the  still  very  great  saturation  ca- 
pacity of  the  fiber  for  the  dye. 

In  the  second  method  the  concentration  of  dye  used  was 
75  mg;  the  kind  and  amount  of  acid  used  in  each  case  was  the 
same,  namely,  10  cc  of  N/io  HC1,  H2SO4  and  H3PO4,  respec- 
tively. The  method  and  other  conditions  of  dyeing  were 
the  same.  Acid  green,  crocein  orange,  and  crystal  ponceau 
were  studied.  The  data,  the  average  of  duplicate  experiments, 
follow : 

TABLE  VI 

Temperature — 100°  C 

75  mg  dye  per  25  cc  H2O 

Time — i  hour 


Bleeding  test. 

Amount  dye  given 

Acid  used 

Dye  ad- 

Dye unad- 

up  by  dyed  fiber 

Dye 

10  cc  of 
each  N/io 

sorbed 
Milli- 

sorbed 
Milli- 

to 250  cc  H2O  at 
boiling  tempera- 

acid 

grams 

grams 

ture  for  20 

minutes 

Milligrams 

Acid  green 

No  acid 

57-9 

17.1 

5-7 

HC1                72.2 

2.8 

4-5 

H2S04            67.4 

7.6 

4-9 

\ 

H3P04 

65.2 

9.8 

5-3 

Crystal  ponceau 

No  acid 

59-8 

15-2 

5-8 

HC1 

74-5 

o-5 

1.8 

H2SO4 

73-2 

1.8 

1.6 

H3P04 

72.3 

2-7 

4.1 

Crocein  orange 

No  acid 

61.8 

13.2 

7.8 

HC1 

72.7 

2.3 

3-9 

H2SO4 

69.4 

5-6 

4-3 

H3P04 

69.4 

5-6 

5-3 

In  discussing  Table  V  it  was  suggested  that  when  the 
capacity  of  a  fiber  for  an  acid  dye  is  as  yet  high  the  effect 
of  an  adsorbed  ion  in  cutting  down  the  adsorption  of  the 
dye  is  largely  overcome.  On  the  other  hand,  a  low  capacity 
of  the  fiber  for  a  dye  should  indicate  that  adsorbed  anions 


788  D.  B.  Lake 

as  the  above  could  bring  about  a  decrease  in  the  amount  of 
acid  dye  adsorbed.  To  denote  this  varying  adsorbing  ca- 
pacity of  a  fiber  under  the  conditions  indicated  above  the  use 
of  the  term  saturation  capacity  is  suggested.  By  the  term 
saturation  capacity  of  the  wool  then  is  meant  the  capacity  of 
the  fiber  to  adsorb  a  given  amount  of  dye  under  definite  con- 
ditions. In  other  words  as  suggested  by  Professor  Bancroft: 
"If  the  amount  of  dye  that  will  be  taken  up  from  a  concen- 
trated solution  is  loo  and  if  x  is  taken  up  from  any  given  con- 
centration, then  TOO  -  -  x  is  the  saturation  capacity  of  the 
latter  solution."  It  is  evident  that  when  the  fiber  has  ad- 
sorbed a  large  amount  of  dye  its  capacity  to  adsorb  more  dye 
(its  saturation  capacity)  is  considerably  less  than  when  it 
has  adsorbed  a  much  smaller  amount  of  dye.  Thus  if  we 

consider  the  two  points  A  and  B  in 
Fig.  i  on  an  adsorption  isotherm  as 
representing  the  amounts,  respectively, 


of  a  dye  adsorbed  by  wool,  it  is  seen 
that  the  fiber  which  had  adsorbed  an 

amount    corresponding    to    A    has    a 

much  larger  capacity  to  adsorb  more 
dye,   and   its    saturation    capacity    is 

much    greater  than    the  same  fiber  which  has  adsorbed  an 
amount  corresponding  to  B. 

If  now  we  compare  the  data  for  the  adsorbed  dye  in 
Table  IV  (40  mg  dye  per  250  cc  H2O)  with  the  corresponding 
data  in  Table  VI,  we  see  strikingly  illustrated  in  the 
first  data  as  compared  with  the  latter  data  the  marked  force 
of  the  fiber  manifested  in  cutting  down  the  repelling  effect 
of  the  adsorbed  anion  on  the  adsorption  of  the  dye.  In 
the  data  of  Table  VI  we  see  that  the  cutting  down  effect  of 
the  phosphate  ion  over  the  sulphate  ion  is  considerable,  with 
the  exception  of  the  crocein  orange.  It  is  to  be  observed  that 
22.1  mg  and  27.8  mg  more  of  crystal  ponceau  and  acid  green, 
respectively,  in  neutral  solutions,  were  adsorbed  by  the  wool 
dyed  in  75  mg  dye  per  250  cc  H2O,  than  were  adsorbed  in 
40  mg  of  the  respective  dyes  per  25  cc  H2O.  This  indicates 


Studies  in  Dyeing  and  Cleaning 


789 


that  the  saturation  capacity  of  the  fiber  for  these  dyes  in  the 
former  case  has  been  so  nearly  reached  as  to  allow  the  cutting 
down  effect  of  the  adsorbed  phosphate  ion  over  the  sulphate 
ion  to  be  manifested. 

The  table  of  comparison  follows : 

TABLE  VII 


Dye 

Acid  used 

Dye  adsorbed  from 
solution  40  mg 
per  250  cc  H2O 
Milligrams 

Dye  adsorbed  from 
solution  75  mg 
per  250  cc  H2O 
Milligrams 

Acid  green 
Crystal  ponceau 
Crocein  orange 

H2S04 
H3P04 
H2S04 
H3P04 
H2SO4 
H3P04 

36.3 
36.0 

39-4 
39-4 

35-5 
35-5 

67.4 
65.2 
73-2 

72.3 
69.4 
69.4 

As  seen  in  the  data,  H2SO4  and  H3PO4  are  equally  efficient 
in  bringing  about  an  adsorption  of  crocein  orange.  Experi- 
ments with  a  higher  concentration  of  the  dye,  100  mg  per 
250  cc  H2O,  show,  however,  that  the  laws  of  adsorption  of  an 
acid  dye  in  an  acid  solution  as  postulated  by  Bancroft  hold. 
The  data  showing  the  effects  of  H2SO4  and  H3PO4  on  the  ad- 
sorption of  the  dye  follow: 

TABLK  VIII 
Temperature — 100°  C 
100  mg  dye  per  250  cc  H2O 
Time — i  hour 


Dye 

Acid  used 
10  cc  N/io 
of  each  acid 

Dye  adsorbed 
Milligrams 

Dye  unadsorbed 
Milligrams 

Crocein  orange 

H2SO4 
H3P04 

92.5 
90.7 

7-5 
9-3 

After  one  of  the  bleeding  tests  carried  on  for  wool  dyed 
in  a  neutral  bath  of  acid  violet  the  dyed  fiber  was  left  in  the 
hot  solution  of  the  dye  that  had  bled  from  the  fiber,  and  the 
whole  allowed  to  cool.  As  the  beaker  and  contents  cooled 


JK  J  Vli 


790  D.  B.  Lake 

it  was  observed  that  the  dye  was  quite  rapidly  readsorbed. 
In  an  hour  practically  all  of  the  dye  had  been  readsorbed. 
This  experiment  was  repeated  for  acid  violet  with  similar  re- 
sults. Experiments  with  fibers  dyed  in  crocein  orange  and 
acid  green  and  treated  as  those  dyed  in  acid  violet  gave  similar 
results,  the  slight  differences  being  (i)  that  not  quite  all  of 
the  dye  that  bled  was  readsorbed,  (2)  that  the  readsorption 
was  slower  than  in  the  case  of  acid  violet.  The  results  of  these 
experiments  seemed  to  indicate  an  irreversible  adsorption  of 
dyes.  That  there  is  also  this  irreversible  adsorption  between 
the  adsorbed  and  unadsorbed  dye  in  direct  dyeing  was  shown 
in  experiments  carried  out  with  acid  violet,  crocein  orange, 
and  acid  green.  One-gram  samples  of  wool  were  dyed  in  60 
mg  acid  violet,  crocein  orange,  and  acid  green  per  250  cc  H2O, 
respectively,  for  one  hour  at  the  temperature  of  the  boiling 
water-bath,  after  which  time  the  beaker  and  contents  (the 
dyed  fiber  was  left  in  the  solution  of  unadsorbed  dye)  were 
allowed  to  cool.  At  the  end  of  ten  hours  all  of  the  acid  violet 
unadsorbed  (about  10  mg)  in  this  direct  dyeing  was  completely 
adsorbed.  The  adsorption  of  the  unadsorbed  crocein  orange 
and  acid  green  was  much  slower.  To  insure  complete  ad- 
sorption of  these  dyes  the  dyed  fibers  were  left  in  the  cold 
dye  bath  (room  temperature)  for  eight  days.  At  the  end  of 
that  time  about  7  mg  of  the  unadsorbed  crocein  orange  in  the 
direct  dyeing  and  10  mg  of  the  unadsorbed  acid  green  were 
adsorbed;  or  in  terms  of  percentage  of  the  respective  unad- 
sorbed dyes  91  percent  of  the  crocein  orange  was  adsorbed, 
and  90  percent  of  the  acid  green. 

Various  experiments  were  made  to  account  for  this  ir- 
reversible adsorption  of  the  dye.  It  was  thought,  although 
improbable,  that  the  wool,  when  heated,  was  in  some  way 
changed  so  that  its  specific  adsorbing  power  had  increased. 
Hence  an  experiment  was  carried  out  in  which  the  wool  was 
placed  in  water  heated  to  the  temperature  of  the  boiling  water-bath 
for  one  hour  and  then  entered  while  hot  in  10  mg  of  acid  violet 
(room  temperature)  in  250  cc  H2O.  After  24  hours  there  was 
no  appreciable  adsorption  of  the  dye.  An  experiment  in 


Studies  in  Dyeing  and  Cleaning  791 

which  the  acid  violet  (10  mg  per  250  cc  H2O)  was  heated  at 
the  same  temperature  for  one  hour  and  then  the  cold  wool 
entered  the  hot  dye  bath  and  the  whole  allowed  to  cool,  gave 
scarcely  better  results  although  slightly  more  dye  was  ad- 
sorbed than  in  the  previous  case.  An  experiment  in  which 
the  wool  and  dye  were  heated  separately,  as  in  the  above, 
for  one  hour  and  then  the  fiber  entered  the  hot  dye  bath, 
gave  similar  results.  A  final  experiment  in  which  the  fiber 
was  dyed  in  60  mg  of  acid  violet  and  then  the  dyed  fiber  re- 
moved from  the  bath  and  entered  again  when  both  were  cooled 
to  room  temperature  resulted  in  an  appreciable  adsorption  of 
acid  violet  at  the  end  of  six  weeks.  Experiments  of  a  similar 
nature  with  acid  green,  11.2  mg  dye  per  250  cc  water,  gave 
negative  results  in  indicating  a  reason  for  this  ir reversibility. 
The  dye,  however,  in  contrast  to  that  of  the  acid  violet,  was 
almost  completely  adsorbed  in  all  cases  at  the  end  of  one  week. 

Although  these  experiments  do  not  seem  to  point  to  any 
reason  for  the  irreversible  adsorption  of  a  dye  they  do  seem 
to  bring  out  the  interesting  fact  that  the  more  irreversible 
a  dye  the  less  completely  and  readily  that  dye  is  adsorbed 
at  low  temperatures.  From  methods  described  below  it  is 
brought  out  that  of  the  dyes  acid  violet  and  acid  green,  acid 
violet  is  far  more  irreversible  than  acid  green.  From  the 
experiments  just  described  above  we  see  that  acid  violet, 
even  after  a  long  period  of  time,  is  adsorbed  very  slightly 
at  room  (low)  temperature.  Niagara  violet  3R,  like  acid 
violet,  is  a  highly  irreversible  dye.  An  experiment  in  which 
a  one-gram  sample  of  wool  was  left  in  a  bath  of  60  mg  of  the 
dye  per  250  cc  water  for  three  weeks  at  room  temperature 
brought  out  the  fact  that  the  dye  was  very  slightly  adsorbed. 
Acid  green  in  contrast  to  the  above  dyes  is  much  more  rever- 
sible, and  hence  was  much  more  largely  adsorbed  at  room  (low) 
temperature. 

That  this  apparent  irreversible  adsorption  of  dyes  is 
quite  general  is  indicated  by  the  work  of  Freundlich  and 
Losev.1  In  four  cases  of  the  six  studied  this  phenomenon 

1  Zeit.  phys.  Chem.,  59,  284  (1907). 


792  D.  B.  Lake 

was  exhibited.  They  found,  for  example,  that  on  wool  patent 
blue  was  irreversibly  adsorbed;  on  silk  new  fuchsin  and 
patent  blue,  and  on  cotton  new  fuchsin.  Crystal  violet  was 
adsorbed  reversibly  by  wool  and  silk. 

The  question  now  arises:  is  there  any  relation  between 
this  apparent  irreversible  adsorption  of  a  dye  and  its  ten- 
dency to  bleed?  If  we  consider  this  irreversible  adsorption 
as  indicative  of  the  force  with  which  the  dye  is  held  by  a 
fiber  it  would  seem  that  the  more  irreversible  a  dye  is  the 
less  that  dye  will  bleed.  Thus,  if  we  consider  the  experi- 
ments described  above  for  acid  violet,  crocein  orange  and  acid 
green  we  see  that  the  irreversibility  of  the  acid  violet  was 
complete:  the  irreversibility  of  the  crocein  orange  and  acid 
green  nearly  equal  to  each  other.  Therefore,  under  like 
conditions  of  dyeing  and  testing  for  bleeding  we  should  ex- 
pect acid  violet  to  bleed  less  from  a  fiber  than  acid  green  or 
crocein  orange;  and  that  the  two  last-named  dyes  should 
bleed  approximately  the  same. 

To  show  the  relationship  between  the  irreversible  ad- 
sorption of  a  dye  and  its  bleeding,  two  methods  of  experi- 
mentation were  carried  out :  ( i )  a  method  suggested  by  Freund- 
lich,  (2)  a  method  suggested  by  Professor  Bancroft.  Freund- 
lich's  method  will  be  taken  up  first.1  One  gram  of  pure  wool, 
used  as  bought,  was  entered  in  250  cc  of  water  containing  60 
mg  of  dye,  and  dyed  for  one  hour  at  the  temperature  of  boiling 
water-bath.  The  dye  unadsorbed  was  determined  colori- 
metrically.  The  dyed  fiber  was  tested  for  bleeding  in  a  volume 
of  250  cc  HzO  for  twenty-five  minutes,  and  the  amount  of 
dye  bled  determined  also  colorimetrically.  Parallel  with  the 
above  experiment  another  one  was  run  in  which  the  same  weight 
of  wool  was  entered^  in  just  one-half  the  volume  of  dye  solu- 
tion containing  the  same  amount  of  dye,  and  dyed  at  the  same 
temperature  for  one  hour.  Then  the  volume  of  solution  was 
made  up  to  250  cc  and  the  whole  heated  at  the  same  tempera- 
ture for  another  hour.  The  amount  of  unadsorbed  dye  in 


Zeit.  phys.  Chem.,  57,  385  (1906). 


Studies  in  Dyeing  and  Cleaning 


793 


this  experiment  was  likewise  determined  colorimetrically. 
Thus  by  these  experiments  a  relation  between  the  irreversi- 
bility  of  a  dye  and  its  bleeding  was  obtained.  The  data, 
the  average  of  triplicate  experiments,  are  given  in  the  table 
below. 


Amount  un- 

Dye 

adsorbed 
after  i-hour 
treatment 
(direct  dye- 
ing) 

Amount  dye 
unadsorbed 
on  irreversible 
experiment 
Milligrams 

Amount  dye 
irreversibly 
adsorbed 
Milligrams 

Amount  dye 
bled 
Milligrams 
IV 

Milligrams 

II 

I 

Crocein  orange 

II  .2 

8.6 

2.6 

5-0 

Acid  green 

7-3 

6-3 

I  .0 

4-4 

Niagara  violet  3R           8.9 

I  .0 

7-9 

O.  I 

These  data  bring  out  the  fact  that  the  more  irreversible 
the  dye  the  less  the  bleeding.  Column  I  gives  the  amount  of 
dye  unadsorbed  by  the  fiber  in  the  first  experiment  as  out- 
lined above.  Column  II  gives  the  amount  of  dye  unadsorbed 
by  the  fiber  which  was  first  entered  in  just  half  the  volume  of 
dye  of  double  the  strength  used  in  the  first  experiment.  After 
one  hour  an  amount  of  water  was  added  making  the  final 
volume  equal  to  that  used  in  the  first  experiment.  It  is  seen 
that  in  all  cases  the  end  concentration  in  the  second  column 
is  less  than  in  the  first  column.  This  indicates  a  certain 
amount  of  irreversible  adsorption  on  the  part  of  the  dye 
under  the  conditions  of  the  experiment,  for  if  there  had  been 
a  definite  equilibrium  between  the  adsorbed  quantities  and 
the  end  concentrations,  the  final  concentration  in  Column  II 
ought  to  have  been  the  same  as  in  Column  I.  Column  III 
gives  the  difference  in  end  concentrations  between  Columns 
I  and  II.  Column  IV  shows  the  amount  of  dye  given  up 
by  the  fibers  in  the  bleeding  test.  In  comparing  Columns  III 
and  IV  we  see  that  for  the  conditions  of  the  experiment  the 
amount  of  dye  irreversibly  adsorbed  is  greater  the  faster 
the  dye  is  to  the  bleeding  test  as  carried  out  in  the  experi- 


794 


D.  B.  Lake 


ment.     There  does  not  seem  to  be  any  quantitative  relation- 
ship between  the  quantities  given  hi  Columns  III  and  IV. 

The  other  method  of  showing  the  irreversible  adsorp- 
tion, as  suggested  by  Professor  Bancroft,  was  as  follows: 
A  one-gram  sample  of  wool  was  dyed  in  a  bath  containing 
60  mg  of  the  dye  for  two  hours  at  90°  C  or  till  equilibrium 
was  reached.  The  fiber  was  then  removed,  washed,  and  the 
amount  of  dye  left  in  the  bath  determined  colorimetrically. 
The  data  are  given  in  Column  I,  of  the  subjoined  table.  The 
dyed  fiber  was  put  in  a  beaker  containing  250  cc  water  and 
the  whole  heated  to  the  temperature  of  the  water-bath  for 
about  25  minutes.  The  beaker  and  contents  were  at  once 
cooled  to  90°  C  and  the  fiber  then  placed  in  another  beaker 
which  contained  in  250  cc  H2O  an  amount  of  dye  that  was 
not  adsorbed  by  the  fiber  during  the  dyeing  at  90°.  The 
whole  was  kept  at  90°  C  till  equilibrium  was  reached,  or  for 
about  two  hours.  The  fibers  were  then  removed,  washed, 
and  the  amount  of  dye  left  in  the  solution  determined  as 
above.  The  data  are  recorded  in  Column  II  in  the  table 
below.  The  difference  between  the  amount  of  unadsorbed  dye 
during  the  direct  dyeing,  and  the  amount  of  dye  in  the  second 
final  dye  bath  is  taken  as  a  measure  of  the  amount  of  it  irre- 
versibly adsorbed.  Column  III  of  the  table  below  contains 
the  data.  The  data,  the  average  of  duplicate  experiments, 
follow : 


Dye 

Dye  unadsorbed 
on  direct  dyeing 
Milligrams 
I 

Dye  unadsorbed 
on  irreversible 
experiment 
Milligrams 
II 

Amount  of  dye 
irreversibly 
adsorbed 
Milligrams 
III 

Crocein  orange 
Acid  green 
Niagara  violet  3R 

7-3 
9-5 
9-5 

6-5 

5-7 

I  .2 

0.8 
3-8 
8-3 

These  data  bring  out  the  same  general  relationship  that 
were  brought  out  in  the  immediately  preceding  table.  Here 
as  there  the  most  irreversible  dye  is  Niagara  violet  followed 
by  acid  green  and  crocein  orange  in  the  order  named. 


Studies  in  Dyeing  and  Cleaning 


795 


These  two  sets  of  experiments  point  to  the  general  con- 
clusion that  the  more  a  dye  is  irreversibly  adsorbed,  other 
factors  being  the  same,  the  less  it  will  bleed  when  subjected 
to  such  tests.  This  is  brought  out  rather  strikingly  in  a 
comparison  of  the  amounts  of  dye  bled  for  crocein  orange  and 
acid  green,  in  Tables  IV  and  VI.  In  five  out  of  the  eight 
cases  compared  crocein  orange  bled  more  than  acid  green. 
This  is  what  one  should  expect  from  a  knowledge  of  the 
comparative  irreversibility  of  the  two  dyes.  The  three 
exceptions  noted  may  be  more  apparent  than  real. 

FROM  TABLE  IV 


Treatment 

Amount  dye  bled 
Milligrams 

Crocein  orange 

Acid  green 

Neutral  bath 
HC1  bath 
H2SO4  bath 
H3PO4  bath 

5-0 
4-4 
3-1 
3-7 

3-9 

2.7 
2.7 
3-3 

FROM  TABLE  VI 


Neutral  bath                            7  .  8 

5-7 

HC1  bath 

3-9 

4-4 

H2SO4  bath 

4-3 

4.8 

H3PO4  bath 

5-3 

5-3 

To  sum  up  this  part  of  the  work : 

This  irreversible  adsorption  of  a  dye,  as  suggested  above 
(page  792),  may  be  taken  as  indicative  of  the  force  with  which 
a  dye  is  held  by  a  fiber.  From  this  point  of  view  one  would 
conclude  that  Niagara  violet  or  acid  violet  is  much  more 
firmly  held  by  the  wool  than  is  crocein  orange  or  acid  green ; 
hence  the  less  bleeding  exhibited  by  the  first  two  named  dyes 
than  the  last  two.  This  force  by  which  the  dye  is  held  by  the 
fiber  is  of  a  selective  nature;  that  is,  there  seems  to  be  no  re- 
lation between  the  constitution  of  a  dye,  and  its  irreversi- 
bility. It  is  possible  that  the  more  irreversible  dyes  act  as 


796  D.  B.  Lake 

better  mordants  toward  themselves  than  the  less  irreversible 

ones. 

Stains  and  Their  Removal 

In  an  experiment  in  which  acid  violet  was  practically, 
although  not  completely,  removed  from  the  fiber  by  boiling 
water  we  have  a  case  analogous  to  the  partial  removal  of  a 
fruit  stain  from  cloth  by  this  same  means  and  method.  Thus 
in  the  experiment  with  acid  violet  we  can  look  upon  the  dye 
as  the  stain  upon  the  wool.  Its  practical  removal  from  the 
fiber  was  due  to  the  fact  that  the  boiling  water  peptized  it, 
that  is,  made  a  colloidal  solution  of  it. 

Dyes  also  can  be  removed  from  a  fiber  by  reagents  other 
than  water,  as,  for  example,  by  the  use  of  bleaching  agents, 
aqueous  solutions  of  ammonium  acetate  or  sodium  carbonate, 
and  solid  reagents  such  as  fullers'  earth.  The  above  reagents 
are  used  also  to  remove  stains  from  textiles,  and  in  many 
instances  the  methods  and  principles  of  removal  of  the  stain 
by  a  given  reagent  is  the  same  as  for  the  dye.  This  very 
interesting  analogy  between  some  stains  and  dyes  with  re- 
gard to  their  behavior  towards  various  reagents  led  to  the 
following  classification  of  the  principles  underlying  the  removal 
of  the  greater  majority  of  stains  from  textiles,  and  to  a  brief 
study  to  confirm  each  method  in  this  classification. 

The  following  classification  has  been  proposed  by  Pro- 
fessor Bancroft: 

I.  Mechanical  removal. 

Mud  and  brush. 
II.   Dissolving  in  a  liquid. 

Grass  in  alcohol,  benzene. 

Sugar  in  water;  dyes  in  hot  water. 

Iodine  in  alcohol. 

Syrup  in  warm  water. 
III.  Peptizing  in  a  liquid. 

Balsam  of  Peru  with  kerosene  or  alcohol. 

Dyes  in  hot  water ;  chocolate  with  hot  water. 

Machine  oil  with  turpentine. 

Grease  with  gasolene. 


Studies  in  Dyeing  and  Cleaning  797 

Glue  with  warm  water. 

Milk  with  cold  water. 

Paraffine  with  benzine  or  kerosene. 

Pitch  with  benzine. 

Vaseline  with  turpentine. 

Punch  with  warm  water. 

Coffee  tannin  with  boiling  water. 

Iron  rust  with  kerosene. 
IV.  Peptizing  with  a  solution. 

Dyes  with  sodium  carbonate,   ammonium  sulphate, 
borax. 

Blood  with  ammonia. 

Soot  with  sodium  hydroxide  (2  percent  solution). 

Glue  with  acetic  acid. 

Paint  with  sodium  carbonate. 
V.  Peptizing  with  peptized  colloid. 

Blood  with  soap. 

Soot,  iron  rust,  with  soap. 

Cream  with  soap. 

Perspiration  with  soap. 

Old  black  silk  clothes  with  skimmed  milk. 

Kerosene  with  soap. 

Meat  juice  with  soap. 
VI.  Peptizing  in  two  stages. 

Tar  and  oil  and  soap. 

Grease  and  oil  and  soap. 

Tea  and  glycerine  and  soap. 

Black  shoe  polish  and  oil  and  soap. 

Grass  and  benzine  and  soap. 

Rosin  and  oil  and  soap. 

Coffee  and  glycerine  and  soap. 

Paint  and  oil  and  soap. 

Paint  and  oil  and  casein  and  soap. 
VII.  Adsorption  by  solid. 

Grease  and  fullers'  earth  or  blotting  paper. 

Wax  and  French  chalk. 


798  D.  B.  Lake 

Starched  white  woolen   shawls,   lace  curtains,   with 
rice  or  potato  starch,  and  treatment  with  enzymes. 
Dyes  and  freshly  prepared  alumina. 
Charcoal  drawings  and  bread. 
Fruit  stains  and  fullers'  earth. 
Fruit  stains  and  salt. 
Wall  paper  and  dough,  corn-meal. 
Furs  and  corn-meal. 
VIII.  Peptizing  with  a  liquid  and  adsorption  by  solid. 

Grease,    alcohol    or    turpentine,    and    pipe-clay    or 

fullers'  earth. 
IX.  Change  of  substance  forming  the  stain. 

Fruit  stains  oxidized  by  use  of  "bleaching"  agents. 

Ink  with  salt  and  lemon  juice. 

Ink  with  hydrochloric  acid,  oxalic  acid. 

Dyes  with  bleaching  agents,  as  sulphur  dioxide. 

Dyes  with  potassium  permanganate  and  oxalic  acid. 

Iron  rust  with  hydrochloric  acid. 

Iron  rust  with  citric  acid  and  cream  of  tartar. 

Perspiration  with  sodium  hyposulphite  (for  silks  and 

wools) . 

Tobacco  with  hydrochloric  acid  and  ammonia. 
These  methods  will  be  taken  up  in  the  order  given. 
Method    I   involves   mechanical   manipulation   only.     The 
efficiency  of  the  brush  depends  upon  the  fact  that  the  material 
to  be  removed  is  generally  held  loosely  by  the  fiber. 

In  Method  II  stains  from  iodine  and  the  dye  safranine 
were  studied. 

With  respect  to  iodine  a  piece  of  woolen  cloth  was  im- 
mersed in  an  aqueous  solution  at  room  temperature  for  thirty 
minutes,  and  another  piece  at  the  boiling  temperature  for 
ten  minutes.  The  iodine  adsorbed  by  the  fiber  at  room  tem- 
perature was  readily  removed  by  alcohol  at  the  same  tempera- 
ture. The  removal  of  the  stain  from  the  boiling  solution  was 
not  brought  about  so  readily  by  alcohol  at  room  temperature, 
a  much  longer  time  being  required,  namely,  about  twenty- 
four  hours.  However,  by  immersion  of  a  similarly  stained 


Studies  in  Dyeing  and  Cleaning  799 

piece  of  cloth  in  several  fresh,  hot  portions  of  boiling  alcohol 
the  removal  of  the  stain  was  brought  about  in  a  short  time. 
Woolen  cloth  was  stained  by  the  dye  safranine  in  the  same 
manner  as  by  the  iodine.  The  larger  part  of  the  dye  adsorbed 
at  room  temperature  was  removed  by  repeated  immersion 
in  fresh  portions  of  water  at  that  temperature.  The  removal 
was  brought  about  more  completely  by  immersion  in  water 
heated  to  6o°-7o°  C.  Not  all  of  the  dye,  however,  was  re- 
moved, even  by  boiling  water — there  being  a  small  portion 
which  ''set"  on  the  fiber. 

The  larger  part  of  the  dye  adsorbed  by  the  fiber  at  the 
temperature  of  boiling  water  was  removed  slowly,  and  only  by 
repeated  immersion  of  the  dyed  fiber  in  fresh  portions  of 
boiling  water.  The  last  traces  of  the  dye  could  not  be  re- 
moved by  this  treatment. 

The  other  cases  listed  in  this  division  of  the  general 
classification  are  removed,  as  safranine  and  iodine  were,  with 
the  formation  of  a  true  solution  of  the  stain  with  the  solvent. 
When  fresh  these  stains  are  quite  readily  removed  by  the 
particular  solvent.  A  stain,  as  grass  stain,  may,  however, 
become  "set"  on  the  fiber  with  the  result,  as  in  the  case  of 
safranine,  that  it  cannot  be  removed  by  the  solvent,  even  by 
repeated  applications.  Chemicals  as  listed  in  IX  are  then 
generally  the  only  reagents  capable  of  bringing  about  its  re- 
moval. The  sugar  and  syrup  stains,  as  is  obvious,  can  easily 
be  removed  by  water  for  they  are  not  strongly  adsorbed  by 
fibers,  and  also  are  very  easily  soluble  in  the  liquid. 

The  cases  studied  where  the  liquid  peptized  the  stain 
were:  the  dye  crocein  orange  removed  by  water;  grease  (lard) 
removed  by  gasolene. 

In  the  case  of  crocein  orange  the  method  of  experiment 
was  identical  with  that  of  safranine.  The  results  obtained 
were  similar;  that  is,  in  no  case  was  the  dye  completely  re- 
moved from  the  fiber.  In  the  case  of  the  fiber  dyed  hot  in 
a  solution  of  60  mg  of  dye  per  250  cc  H2O  for  one  hour,  repeated 
immersions  of  the  dyed  fiber  in  fresh  boiling  water  removed 
the  greater  part  of  the  dye  only  after  4x/2  hours. 


8oo  D.  B.  Lake 

Grease  was  completely  removed  by  gasolene  in  a  very 
short  time  at  room  temperature. 

Peptization  of  substances  by  a  liquid  as  in  the  above 
cases  is  a  very  common  phenomenon.1  In  the  cases  of  the 
fiber  stained  either  by  the  dye  or  grease  we  may  look  upon 
the  combination  as  one  substance.  Thus  with  the  dyed  fiber 
it  adsorbs  the  solvent  water,  and  so  part  of  it,  i.  e.,  the  colored 
portion,  is  peptized.  Hence  we  get  a  water-soluble  colloid 
of  the  dye.  The  same  holds  for  the  greased  fiber.  It  readily 
adsorbed  the  gasolene  and  hence  part  of  it  was  peptized, 
with  a  formation  of  a  gasolene- soluble  colloid  of  grease.  To 
quote  Professor  Bancroft,  "If  we  wash  out  of  cloth  a  dye 
which  forms  a  colloidal  solution2  we  are  peptizing  the  dye 
with  water.  The  removal  of  chocolate  by  water  is  another 
case  of  the  same  type  because  chocolate  does  not  really  dis- 
solve in  water.  The  removal  of  iron  rust  from  iron  by  means 
of  kerosene  is  a  case  of  peptization  because  the  iron  oxide  does 
not  dissolve  in  kerosene.  The  removal  of  grease  by  benzine, 
gasolene,  naphtha,  etc.,  is  another  case  under  this  heading 
because  the  grease  does  not  form  a  true  solution  in  these  or- 
ganic liquids.  The  removal  of  resin  with  benzine  comes 
under  the  same  head." 

Just  as  crocein  orange  was  removed  from  the  fiber  by 
water,  just  as  grease  was  removed  from  the  fiber  by  gasolene, 
so  the  other  substances  here  listed  as  stains  are  removed  in 
the  same  way  by  the  particular  peptizing  solvent.  Colloidal 
solutions  are  formed  in  all  cases.  Thus  with  water  we  have 
formed  the  water-soluble  colloids  of  coffee,  glue,  milk,  and 
punch;  with  turpentine  we  have  the  turpentine-soluble  col- 
loids of  machine  oil  and  vaseline;  with  kerosene  the  kerosene- 
soluble  colloids  of  paraffine,  pitch,  and  iron. 

Many  stains  can  be  removed  from  fibers  by  means  of 
dissolved  substances.  This  removal  is  due  to  the  fact  that 
the  undissociated  dissolved  substance,  or  one  of  the  products 
of  the  dissolved  substance,  is  readily  adsorbed  by  the  stain 

1  Bancroft:  Jour.  Phys.  Chem.,  20,  85  (1916). 

2  Bancroft:  Journal  of  Home  Kconomics,  8,  356  (1916). 


Studies  in  Dyeing  and  Cleaning  80 1 

and  hence  peptizes  it,  thus  giving  rise  to  a  colloid  solution. 
In  aqueous  solutions,  in  general,  peptization  by  undissociated 
substances,  as  for  example,  inorganic  salts,  is  not  so  well  de- 
fined as  peptization  by  an  ion.1  Cases  of  peptization  by 
an  ion,  however,  are  numerous  and  well  known.  Thus  the 
removal  of  the  stains  as  listed  in  IV  can  be  considered  as 
brought  about  by  their  peptization  by  ions.  Thus  in  the  case 
of  the  blood  stains  their  removal,  from  this  point  of  view,  is 
due  to  the  peptization  of  the  haemoglobin  of  the  blood  by 
the  adsorbed  hydroxyl  ions  from  the  aqueous  solution  of  am- 
monia. Acid  dyes  can  readily  be  removed  from  wool  by  a 
dilute  solution  of  borax.  The  borax  in  solution  is  hydrolyzed 
giving  rise  to  the  formation,  among  other  substances,  of  sodium 
hydroxide,  which  in  turn  dissociates  into  sodium  and  hydroxyl 
ions.  Now  the  hydroxyl  ions  are  preferentially  and  readily 
adsorbed  by  the  stained  fiber,2  hence  they  readily  peptize 
the  adsorbed  acid  dye,  and  its  removal  in  consequence  is 
brought  about. 

In  the  laboratory  an  example  studied  under  this  section 
(IV)  was  the  removal  of  soot  by  a  dilute  solution  of  sodium 
hydroxide  (2  percent).  A  piece  of  cotton  cloth  was  very 
thoroughly  impregnated  with  soot  and  then  immersed  in  the 
slightly  warmed  alkali  solution.  In  a  few  minutes  the  soot 
was  practically  removed  from  the  cloth.  In  this  case  we 
have  the  peptization  of  the  soot  by  the  preferentially  ad- 
sorbed hydroxyl  ions,  giving  rise  to  a  sodium  hydroxide- 
soluble  colloid  of  soot. 

The  removal  of  soot  as  listed  in  V  was  very  interesting. 
Fibers  of  wool  and  silk  were  thoroughly  impregnated  with 
soot  and  then  immersed  in  a  dilute  "liquid"  soap  solution  which 
was  heated  to  about  50°  C.  The  removal  of  the  soot  from 
the  wool  was  very  rapid  and  complete.  In  the  case  of  the 
silk  a  longer  time  was  required  but  the  removal  was  as  com- 
plete. To  quote  Professor  Bancroft  in  this  connection,3 

1  Bancroft:  Jour.  Phys.  Chem.,  20,  102  (1916). 

2  Bancroft:  Ibid.,  18,  10  (1914). 

3  Bancroft:  Journal  of  Home  Economics,  8,  356  (1916). 


802  D.  B.  Lake 

"Under  peptization  by  a  peptized  colloid  we  have  all  the  cases 
in  which  soap  is  used.  Soap  does  not  dissolve  in  water  but 
is  readily  peptized  by  it.  The  theory  of  washing  with  soap 
has  been  put  on  a  satisfactory  basis  by  Spring.1  It  is  to  him 
that  we  owe  a  very  striking  and  instructive  experiment.  If 
we  filter  a  fine  suspension  of  rouge  or  soot  through  filter  paper, 
some  of  the  particles  stick  to  the  filter  paper  or,  as  we  say, 
are  adsorbed  by  it.  If  the  liquid  is  filtered  several  times 
through  the  same  paper,  the  water  will  finally  run  through 
clear,  the  particles  of  rouge  or  soot  adhering  to  the  previously 
adsorbed  particles  and  finally  clogging  the  pores  of  the  filter 
paper.  If  a  soap  solution  be  poured  on  the  filter,  a  red  or  a 
black  filtrate  is  obtained  at  once,  almost  as  though  one  had 
punched  a  hole  in  the  bottom  of  the  filter  with  a  glass  rod. 
The  soap  forms  a  film  round  the  rouge  or  the  soot,  removing 
the  particles  from  the  paper  and  thus  allowing  them  to  pass 
through.  All  the  rest  of  the  particles  follow  just  as  a  log  jam 
breaks  when  the  key  log  is  started.  At  first  sight  it  seems  as 
though  the  soap  must  have  broken  up  the  carbon  or  the  rouge 
into  finer  particles  which  then  passed  through  the  filter.  There 
are  two  reasons  for  rejecting  this  hypothesis.  In  the  first 
place  the  experiment  does  not  succeed  if  the  rouge  or  the  carbon 
is  too  coarse,  and  there  is  no  apparent  reason  why  the  soap 
should  not  break  up  coarse  particles  if  it  can  break  up  fine 
ones.  In  the  second  place  Spring  showed  that  we  are  dealing 
with  an  adsorption  of  soot  by  filter  paper.  If  the  black  filter 
paper  be  reversed  and  washed  with  water,  only  the  carbon 
which  is  not  in  immediate  contact  with  the  paper  is  removed. 

"Soap  acts  in  a  similar  way  in  removing  dirt  or  grease 
from  fabrics  or  from  the  hands.  The  soap  forms  a  film  round 
the  dirt  or  the  grease  removing  it  from  actual  contact  with  the 
fiber  or  the  skin,  thus  simplifying  the  task  of  washing  it  away 
with  water." 

Another  colloidal  solution  which  acts  like  soap  is  ox-gall 
in  water.  Owen  recommends  it  for  the  purpose  of  cleaning 


1  Zeit.  Kolloidchemie,  4,  161   (1909);  6,  n,  109,  164  (1910). 


Studies  in  Dyeing  and  Cleaning  803 

wool  carpets.1  He  says:  "Take  them  and  beat  and  shake 
them  thoroughly  in  a  good  breezy  place  to  get  out  all  dust. 
Have  the  floor  scoured  clean  and,  when  dry,  replace  the  carpet, 
and,  if  still  much  soiled  and  dingy,  go  all  over  the  carpet  with 
ox-gall  and  water.  The  secret  of  success  is  to  clean  and  rinse 
them  thoroughly  without  soaking  them  through.  A  pint 
of  fresh  ox-gall  is  put  into  a  pail  of  clean  soft  water  and  another 
pail  of  clean  water  set  handy.  With  a  brush  rub  up  a  lather 
upon  about  a  square  yard  of  the  carpet  by  dipping  the  brush 
in  the  ox-gall  and  scrubbing,  not  too  hard  but  with  just  the 
movement  that  raises  a  lather,  but  does  not  remove  the  fiber 
from  the  carpet.  Now  with  a  soft  cloth  or  large  sponge,  not 
too  wet,  remove  the  lather,  aiming  to  do  this  by  frequent 
wringing  out  of  the  sponge  in  clear  fresh  water.  After  all  is 
done,  open  the  windows  and  the  carpet  will  soon  dry  out." 

It  is  obvious  that  the  other  substances  listed  in  this 
section  are  removed  in  the  same  way  as  soot  was  by  the  soap. 
In  all  cases  with  the  exception  of  the  stains  on  the  black 
silk  clothes,  the  water-soluble  colloid,  soap,  is  the  effective 
detergent.  Old  black  silk  clothes  can  be  "renovated"2 
by  immersing  them  in  scalding  hot  skim  milk  and  water  to 
which  a  little  glue  or  gelatine  has  been  added.  In  this  case 
the  dirt  and  dust  are  readily  removed  by  the  peptized  colloid 
casein  in  the  milk  and  the  peptized  gelatine. 

It  would  seem  that  soluble  colloids  other  than  water  could 
be  used  to  remove  stains.  Thus  many  aniline  dyes  that  are 
insoluble  in  benzene  "can  be  peptized  by  a  benzene-soluble 
colloid  such  as  zinc  or  magnesium  resinate  so-called."3 

In  the  method  of  peptizing  in  two  stages  the  following 
cases  as  listed  under  VI  were  studied:  grease  and  oil  and 
soap;  rosin  and  oil  and  soap;  paint  and  oil  and  soap;  and 
paint,  and  oil  and  casein  and  soap.  The  methods  suitable 
for  the  above  cases  are  practically  identical  for  the  other  stains 
listed  in  this  section. 


1  "The  Dyeing  and  Cleaning  of  Textile  Fabrics,"  100  (1909). 

2  Owens:  "The  Dyeing  and  Cleaning  of  Textile  Fabrics,"  114  (1909). 

3  Bancroft:  Jour.  Phys.  Chem.,  20,  108  (1916). 


804  D.  B.  Lake 

To  study  the  removal  of  grease  and  rosin  according  to 
the  outline  suggested  white  woolen  cloth  was  thoroughly  im- 
pregnated with  automobile  grease.  These  stained  pieces  of 
cloth  were  then  very  thoroughly  rubbed  with  olive  oil  till 
the  stains  were  softened.  The  whole  was  finally  immersed  in 
a  warm  soap  solution.  The  removal  of  both  stains  was  thor- 
ough and  complete. 

With  regard  to  paint  stains  the  following  procedure  was 
followed:  A  large  piece  of  white  woolen  cloth  was  thor- 
oughly impregnated  with  a  brown  paint,  which  was  allowed 
to  dry  thoroughly  on  the  fiber  by  placing  in  a  hot  air  oven  heated 
to  about  100°  C.  After  the  paint  had  completely  dried,  the 
stained  cloth  was  thoroughly  rubbed  with  olive  oil  till  the 
paint  was  softened.  The  cloth  was  then  cut  into  two  parts. 
One  piece  of  the  cloth  was  immersed  in  a  warm  soap  solution 
for  about  five  minutes.  It  was  then  removed,  washed,  rubbed 
with  oil,  and  again  immersed  in  the  soap  solution.  The  re- 
moval of  the  paint  was  fairly  complete.  The  other  piece  of 
cloth  before  the  soap  treatment  was  treated  with  casein  by 
rubbing  into  it  the  finely  divided  powder.  Treatment  with 
a  warm  soap  solution  then  followed  for  about  five  minutes  as 
in  the  preceding  case.  The  treatment  with  oil  and  casein 
was  repeated  for  this  piece  of  cloth.  If  anything,  the  paint  in 
this  latter  case  was  more  completely  removed  than  it  was  from 
the  other  sample. 

It  might  be  well  in  this  connection  to  quote  Owens.  He 
says,  p.  90:  "Grease  spots  are  of  the  most  common  occur- 
rence. To  remove  these  from  white  fabrics  is  comparatively 
easy,  but  to  remove  them  from  colored  fabrics  without  at  the 
same  time  doing  injury  to  the  color  is  often  very  difficult  and 
sometimes  impossible.  Very  much  depends  upon  the  skill 
and  perseverance  of  the  operator.  Good  soap  and  water  is 
the  most  universal  solvent  for  greasy  matters,  and  where  there 
is  no  reason  for  not  wetting  the  goods,  soap  and  water  should 
be  tried.  Grease  spots  from  carriage  wheels,  sewing  machines, 
or  any  source  containing  iron  from  wear  of  bearings,  or  carbon 
from  any  source,  red  lead,  or  any  insoluble  colored  substance, 


Studies  in  Dyeing  and  Cleaning  805 

should  first  be  rubbed  thoroughly  with  some  oil  that  is  itself 
capable  of  being  washed  out  with  soap  and  water,  such  as 
lard  or  fresh  butter,  olive  oil,  linseed  oil,  etc. 

"Much  depends  on  how  this  is  done.  Don't  be  afraid 
to  use  plenty  of  oil,  butter,  or  lard,  and  then  work  with  the 
fingers,  bending  the  cloth  back  and  forth  as  if  you  were  breaking 
a  wire,  until  upon  holding  it  up  to  the  light  you  see  that  the 
dark  matter  of  the  spot  is  completely  and  evenly  distributed 
and  worked  up  with  the  oil.  When  sure  this  result  is  accom- 
plished, then  work  in  a  thick  cold,  watery,  soapy  mass  obtained 
by  boiling  up  sliced  laundry  soap  in  water  and  allowing  to 
cool.  If  on  touching  the  dry  soap  bar  to  the  tongue,  it  does 
not  'bite,'  it  should  have  some  sal-soda  added  to  it  in  the  boil- 
ing. Work  the  prepared  soap  into  the  cloth  where  the  spot 
is,  until  the  oil  in  its  turn  is  worked  up  with  the  soap  as  thor- 
oughly as  the  spot  was  with  the  oil.  Now,  and  not  before, 
wash  out  the  spot  with  soapy  water.  Only  with  very  old 
spots  will  any  trace  remain  after  this  treatment.  Grease 
spots  succumb  very  well  if  rubbed  up  with  kerosene,  the  kero- 
sene rubbed  up  with  new  milk,  and  the  whole  then  worked 
with  soap  and  water." 

In  regard  to  paint,  Owens  says,  p.  103:  "Paint,  when 
fresh,  washes  out  as  readily  as  any  grease  spot.  As  it  ages 
and  oxidizes  it  becomes  more  and  more  difficult  to  soften  and 

remove  it Oil  the  spot  and  rub  the  oil  in  patiently, 

striving  to  blend  the  spot  with  the  oil.  If  the  spot  is  very  old, 
allow  to  lie  with  the  oil  upon  it  for  several  days,  rubbing 
occasionally  to  see  if  the  paint  is  softening.  A  few  drops  of 
turpentine,  kerosene,  or  any  solvent  for  greasy  matters  may 
be  added  and  worked  in.  Old  lead  paint  is  very  persistent. 
Finally,  wash  out  like  a  fresh  grease  spot." 

In  all  of  these  cases  we  have  as  a  result  of  the  oil  treat- 
ment a  peptization  of  the  particular  stain  by  the  oil.  The 
peptized  stain  was  then  finally  removed  by  the  peptized  col- 
loid, namely,  the  soap  as  explained  in  V.  In  the  case  where 
casein  was  used  we  have  an  adsorption  by  the  casein  of  the 
peptized  paint  followed  by  a  peptization  of  the  casein  and  its 


806  D.  B.  Lake 

adsorbed  products  by  the  soap,  and  their  consequent  removal. 

In  Method  VII  we  have  an  interesting  procedure  for  the 
removal  of  stains  in  that  advantage  is  taken  of  the  greater 
selective  adsorptive  power  of  the  solid  reagent  for  the  par- 
ticular stain  than  the  cloth  or  material  to  be  cleaned.  The 
only  case  studied  was  the  removal  of  grease  by  blotting  paper. 
A  piece  of  cloth,  thoroughly  stained  with  automobile  grease, 
was  placed  between  two  hot  pieces  of  blotting  paper.  The 
grease  was  removed  very  rapidly  from  the  cloth.  Here,  of 
course,  the  adsorptive  power  of  blotting  paper  for  the  grease 
was  greater  than  the  cloth,  hence  the  removal  of  the  grease. 

The  use  of  solid  reagents,  other  than  the  one  studied, 
for  removing  stains  is  quite  general  as  the  list  in  VII  indicates. 
Just  before  using,  these  solid  reagents  should  be  moistened.1 
They  should  be  thoroughly  rubbed  into  the  stained  cloth. 
Repeated  applications  of  the  solid  reagent  will  often  bring 
about  a  complete  removal  of  a  stain.  Koller2  states  that 
infusorial  earth  is  especially  to  be  recommended  for  cleaning 
glass  plates  for  photographic  purposes.  Even  very  greasy 
plates  rapidly  become  clean  when  rubbed  with  infusorial  earth 
moistened  with  water.  A  very  interesting  case  to  be  listed 
under  Method  VII  is  the  removal  of  dirt,  etc.,  from  starched 
curtains.  This  method  was  brought  to  the  attention  of  Pro- 
fessor Bancroft  by  Mr.  C.  P.  Long  of  the  Globe  Soap  Company. 
Starched  lace  curtains  are  placed  in  water  with  a  diastase 
which  converts  the  starch  into  soluble  starch.  When  this  is 
peptized  by  water  the  dirt  comes  off  with  the  starch  without 
any  rubbing. 

In  Method  VIII  we  have  an  example  where  the  stain  is 
first  peptized  by  a  liquid  and  the  removal  of  the  whole  brought 
about  by  selective  adsorption.  As  in  Method  VII  a  piece 
of  wool  cloth  was  stained  with  automobile  grease  and  then 
thoroughly  rubbed  with  alcohol.  Fullers'  earth  was  then 
rubbed  in  and  the  whole  washed  in  cold  water.  By  repeated 


1  Ray  Balderston:  "Laundering,"  47  (1914). 

2  "The  Utilization  of  Waste  Products,"  310  (1915). 


Studies  in  Dyeing  and  Cleaning  807 

applications  of  alcohol  and  fullers'  earth  a  large  percentage 
of  the  grease  was  removed. 

Method  IX  is  resorted  to  among  practical  cleaners,  only 
with  white  goods,  or  where,  with  dyed  goods,  it  is  believed 
that  they  can  be  re-dyed  on  the  spot  thus  treated.  The  re- 
moval of  the  stain  in  this  case  is  brought  about  by  its  conver- 
sion into  other  substances  which  readily  can  be  removed  from 
the  goods  by  washing. 

Iodine  and  safranine  stains  were  studied.  In  the  case 
of  safranine  a  sample  of  cloth  was  taken  upon  which  were 
traces  of  the  dye  which  could  not  be  removed  by  boiling 
water.  The  sample  was  immersed  in  a  dilute  solution  of 
bleaching  powder.  In  a  short  time  the  cloth  was  "bleached." 
Upon  washing,  no  evidence  of  the  dye  was  visible. 

The  sample  of  cloth  stained  by  iodine  was  immersed  in  a 
dilute  solution  of  sodium  thiosulphate.  The  iodine  was  re- 
duced very  rapidly,  and  on  washing  the  cloth  no  evidence  of 
the  stain  was  visible. 

These  two  methods  are  only  suggestions  of  the  many 
cases  where  "chemicals"  may  be  used  for  removing  stains.  In 
their  use  proper  regard  for  the  kind  of  cloth,  silk,  wool,  or 
cotton,  the  condition  of  the  cloth,  as  for  example  whether 
dyed  or  not,  must  be  taken  into  consideration.  One  of  the 
most  frequent  uses  made  of  this  general  method  of  removal 
is  in  the  removal  of  "stubborn"  fruit  stains  as  peach,  plum, 
or  coffee  stains. 

Summary 

Under  the  experimental  conditions  described  the  color  of 
one  dye  can  be  partially  or  completely  masked  by  another, 
but  one  dye  cannot  be  displaced  by  another.  The  apparent 
displacement  is  brought  about  by  the  solvent  or  peptizing 
action  of  the  water. 

An  experiment  is  described  illustrating  the  selective  ad- 
sorption by  wool  of  one  dye  over  the  other  at  different  tempera- 
tures. 

With  respect  to  the  bleeding  of  acid  dyes,  it  is  shown  that 
the  minimum  amount  of  dye  is  extracted  by  hot  water  when 


808  D.  B.  Lake 

the  fiber  (wool)  is  dyed  in  an  acid  bath.  The  most  probable 
reason  for  this  is  that  the  acid  aids  in  coagulating  or  setting 
the  dye  on  the  fiber,  thus  making  it  less  soluble. 

The  laws  of  adsorption  of  an  acid  dye  in  various  acid 
baths  as  postulated  by  Bancroft  hold  when,  as  suggested, 
the  saturation  capacity  of  the  fiber  has  been  so  decreased  that 
the  cutting-down  effect  of  the  respective  anions  can  be  mani- 
fested. 

Of  the  dyes  studied  the  more  the  dye  was  irreversibly 
adsorbed  the  less  completely  and  readily  was  that  dye  adsorbed 
at  a  low  (room)  temperature. 

Of  the  dyes  studied  by  Brown  the  decreasing  or  increasing 
adsorption  with  decreasing  temperature  below  60°  may  be 
accounted  for,  in  view  of  the  immediately  preceding  statement, 
by  postulating  that  those  dyes  are  irreversibly  adsorbed  to 
a  greater  or  less  degree,  rather  than  by  postulating  that  those 
dyes  are  adsorbed  with  an  adsorption  or  evolution  of  heat. 

The  more  a  dye  is  irreversibly  adsorbed,  other  factors 
being  the  same,  the  less  it  will  bleed  when  subjected  to  bleeding 
tests. 

A  classification  of  the  methods  for  the  removal  of  stains 
is  suggested.  A  study  was  made  of  each  method  in  the 
classification.  It  is  suggested  that  a  very  interesting  field 
for  research  in  washing  and  cleaning  is  by  a  study  of  the  method 
belonging  under  Class  VII. 

This  thesis  was  carried  out  under  the  direction  of  Pro- 
fessor Wilder  D.  Bancroft.  It  is  a  pleasant  duty  to  me  to 
express  to  Professor  Bancroft  my  gratitude  for  his  helpful 
criticism,  his  unfailing  kindness  and  courtesy  during  the 
progress  of  the  work. 

Thanks  are  due  to  Professor  Lewis  Knudson,  of  the  New 
York  State  College  of  Agriculture,  for  his  hospitality  in  sharing 
with  me  his  laboratory  after  the  loss  of  Morse  Hall;  and  also 
to  Mr.  W.  B.  White,  of  the  College  of  Agriculture,  for  the  loan 
of  a  Duboscq  colorimeter. 

Cornell  University  \ 


NOV 


21980 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


